Lilies of Blood

The flora of southern Africa is renowned for being remarkably diverse and, in many cases, remarkably eye-catching. The region is home to more than its fair share of ornamental plants, many of which have become popular garden subjects. Among the remarkable members of the southern African flora are the blood lilies of the genus Haemanthus.

Haemanthus coccineus, copyright Peter Coxhead.

Haemanthus is a genus of 22 known species found in the very southern part of the continent, in the countries of South Africa and Namibia (species from further north that have historically been included in Haemanthus are now treated as a separate genus Scadoxus). It is a member of the belladonna family Amaryllidaceae and, like many other members of that family, grows as a herb from a fleshy bulb that is partially or entirely concealed underground. The plant above ground may be annual or persistent, depending on species. Each individual Haemanthus plant produces very few leaves at a time: two is the most common number (Van Jaarsveld 2020). The leaves are more or less fleshy, often hairy, and may be directed upwards or spread outwards.

In those species that shed their leaves, flower stalks are produced before the next season's leaves appear, in a similar matter to the related naked ladies Amaryllis belladonna. Flowers are produced in dense umbels, subtended by bracts that are often brightly coloured, so at a glance the inflorescence of some species might be taken for a single large flower up to ten centimetres in diameter. Depending on the species, the supporting stalk may vary from over a foot in height to only a few centimetres. The first species to be described bear flowers of a bright red colour, explaining both the genus and vernacular names, but flowers may also be pale pink or white. Species that lack the red colour may be referred to as 'paintbrush lilies' rather than 'blood lilies'. Fruits are soft fleshy berries.

Haemanthus albiflos, copyright Krzysztof Ziarnek, Kenraiz.

Phylogenetic analyses of the genus have identified two major clades, a mostly eastern clade found in regions with summer rainfall and a mostly western clade associated with winter rainfall. A notable outlier is the eastern summer-rainfall species H. montanus which is the sister taxon to the winter rainfall clade. Members of the summer-rainfall clade have white or pale pink flowers; members of the winter-rainfall clade have pale pink to dark red flowers. Members of both clades have been grown as pot plants for their unusual appearance though the scent of the flowers is not regarded as pleasant. Perhaps the most widely grown species is H. albiflos, a species native to both the western and eastern parts of South Africa that bears flowers in umbels up to seven centimetres wide. This species is evergreen, carrying its leaves year-round.

REFERENCE

Van Jaarsveld, E. 2020. Haemanthus. In: Eggli, U., & R. Nyffeler (eds) Illustrated Handbook of Succulent Plants: Monocotyledons 2^nd ed. pp. 441–443. Springer.

Woolly Orchids

The orchids of the Orchidaceae are widely recognised as one of the most diverse families of plants in the modern world, both in number of species and morphologically. They are readily distinguished from other flowering plants by a unique combination of features including the fusion of the male and female organs of the flower into a central column. Rather than being released as individual grains, pollen is aggregated into compact masses called pollinia that are attached to pollinators as whole units. Most orchid species also have the lower of the flower's three petals enlarged and differentiated into a distinctive lip that may present a bewildering array of shapes and colours. Because of their striking and colourful appearance, many orchids have long attracted attention from humans and many are popular ornamentals. But there are also some major groups of orchids that have been more neglected and one such group is members of the subtribe Eriinae.

Dendrolirium tomentosum, copyright Orchi.

The Eriinae comprise about a thousand known species of orchid found mostly in the tropics of Asia and the west Pacific, with a handful of species described from Africa. Most are epiphytes and lithophytes (growing on rocks); a smaller number are terrestrial. Because the flowers of eriines tend to be fairly small and simple, they have attracted less notice than other members of the family, but in some parts of their range they are among the most abundant epiphytic orchids (Ng et al. 2018). Within the Orchidaceae, eriines are a subgroup of the subfamily Epidendroideae, characterised by compact, laterally compressed pollinia, and the tribe Podochileae, with duplicate leaves, a short and massive column, and often spherical silica cells in the stems (Szlachetko 1995). The features distinguishing Eriinae from other subtribes of Podochileae are more vague and there are reasons to believe the Eriinae ultimately represent the paraphyletic residue of the tribe once the more specialised subgroups are removed (Ng et al. 2018). One recent classification of the orchids recommended abandoning subtribes within the Podochileae altogether (Chase et al. 2015). Nevertheless, features characteristic of most eriines include a terminal or upper lateral inflorescence, eight pollinia per flower, and sticky caudicles on the pollinia composed of apical pollen grains. The lip is commonly divided into three lobes. Another common feature of the group (and the inspiration for the name of the type genus Eria, meaning 'woolly') is a covering of hairs on the flower and sometimes the inflorescence. In one genus, Trichotosia, the leaves are also hairy.

Ascidieria grandis, copyright Dick Culbert.

Historically, the majority of eriines have been included in a broad genus Eria. However, as with the subtribe as a whole, recent studies have indicated that this sense of Eria is not monophyletic and hence its species should probably be divided between several genera. Ng et al. (2018) recognised 21 genera among the eriines. The African species, previously placed in their own genus Stolzia, were united with the closely related Asian genus Porpax.

The pollination biology of eriines is, for the most part, not well known. Some have speculated that they were pollinated by beetles; one website I found showed pollinia attached to a gnat. The two species of the genus Callostylis have flowers whose appearance suggests pollination by pseudocopulation (tricking male insects into attempting to mate with them by mimicking females) but such flowers are unique within the Podochileae (Ng et al. 2018). At least some eriines have flowers producing 'pseudopollen' from broken-off hairs (Pansarin & Maciel 2017). This pseudopollen is collected and eaten by pollinators. Thus, though the most common means of attracting pollinators among orchids is via deception, at least some eriines are willing to pay their way in life.

REFERENCES

Ng, Y. P., A. Schuiteman, H. A. Pedersen, G. Petersen, S. Watthana, O. Seberg, A. M. Pridgeon, P. J. Cribb & M. W. Chase. 2018. Phylogenetics and systematics of Eria and related genera (Orchidaceae: Podochileae). Botanical Journal of the Linnean Society 186: 179–201.

Pansarin, E. R., & A. A. Maciel. 2017. Evolution of pollination systems involving edible trichomes in orchids. AoB Plants 9: plx033.

Szlachetko, D. L. 1995. Systema Orchidalium. Fragmenta Floristica et Geobotanica Supplementum 3: 1–152.

A Slipper of the Lip

The world of flowering plants includes many unusual and eye-catching examples but even among all this variety the orchids often stand out. Their remarkable array of colours and forms have long fascinated people around the world. One of the more distinctive of orchid subgroups is the Cypripedioideae, commonly known as the slipper orchids.

Pink slipper orchids Cypripedium acaule, copyright Sasata.

Slipper orchids get their name from their most easily recognisable feature, a flower with a deeply saccate labellum or lip (the lower of the three petals) that is supposed to resemble a slipper (an analogy presumably settled on because the alternative of 'scrotum orchid' doesn't have the same ring to it). Like many other orchids, slipper orchids attract pollinators through deception rather than offering a genuine reward. Pollinators are enticed into entering the lip through its large central opening but find themselves unable to exit the same way (presumably because of the way that the rim of the opening curls inwards). Instead, they are forced to make their exit through one of two smaller openings at the base of the lip where it joins the flower's central column. As the pollinator exits this way, it must crawl past the stigma and stamens, removing any pollen it might already be carrying and depositing a new load.

Dwarf slipper orchid Cypripedium fargesii, copyright Steve Garvie.

The exact manner in which the pollinator is lured in varies by species and target (Pemberton 2013). Many produce odours that mimic legitimate nectar-producing flowers or potential food sources such as carrion. A group of species in the genus Cypripedium that are pollinated by bumble bees have low-growing flowers with a purple lip whose main opening appears black. They therefore resemble the opening of a mouse-hole of the type bumble bees use as nest sites. The North American Cypripedium fasciculatum produces a mushroom-like smell that attracts diapriid wasps that parasitise fungus gnats. Some species of the genus Paphiopedilum have light-coloured spots or warts on the flower that are mistaken for a colony of fat, healthy aphids by egg-laying hover flies seeking a food source for their larvae. Perhaps one of the oddest known set-ups is found in the species Cypripedium fargesii whose hover fly pollinator normally feeds on fungal spores. The orchid lures the fly in with patches of hairs on its leave that resemble a fungal infection. A few slipper orchid species are known to be habitually self-pollinating without the intervention of a pollinator; one such species, the South American Phragmipedium lindenii, has lost the slipper-shaped labellum and instead has a lip resembling the other petals.

Selenipedium dodsonii, a species only described as recently as 2015, copyright Andreas Kay.

Slipper orchids have been recognised as a distinct group from other orchids since at least 1840. A number of features isolate them from other orchids, such as their possession of two functional stamens (most other orchids have flowers with only a single stamen). More recent phylogenetic studies have corroborated their position as one of the earliest-diverging orchid lineages. Over 170 species of slipper orchid are currently known, divided by most authors between five genera; most of these genera have widely separated geographic ranges. The genera Selenipedium and Cypripedium have plicate leaves (that is, leaves that are folded within the bud several times longitudinally, in the manner of a fan) that are widely spaced along a well-developed stem, and a prominent rhizome (Rosso 1966). Selenipedium is a small genus found in northern South America that may reach heights of five metres. It differs from the more diverse Cypripedium in having trilocular ovaries and a commonly branching stem; Cypripedium, with over fifty species found across the Holarctic region, has unilocular ovaries and never branches. Cypripedium is the most widely distributed of the slipper orchid genera; the North American C. passerinum may even be found growing in tundra.

Paphiopedilum Leeanum, a cultivated hybrid originally developed in Britain in the 1880s, copyright David Eickhoff.

Phylogenetic analysis of the slipper orchids places Selenipedium as the sister group of the other genera with Cypripedium the next to diverge (Cox et al. 1997). The remaining three genera likely form a single clade united by the possession of a condensed rhizome and conduplicate leaves (folded once in the bud along the midline) arranged in a basal rosette. Paphiopedilum is the most speciose genus of slipper orchids with over ninety species found in India and southeastern Asia; it is also the genus most commonly found in cultivation. Phragmipedium includes over 25 species found in Central and South America; one of these, the Peruvian P. kovachii, has the largest known flowers of any slipper orchid, reaching twelve centimetres in diameter. The third genus Mexipedium, includes a single species M. xerophyticum found in Oaxaca state in Mexico. The three conduplicate-leaved genera are less distinct than the other two genera (one notable distinction is that Phragmipedium has trilocular ovaries whereas those of Paphiopedilum and Mexipedium are unilocular) and it has been suggested that they should be merged into a single genus. Nevertheless, not only are they all geographically distinct, they are supported as monophyletic by molecular analysis (Cox et al. 1997).

Phragmipedium caudatum, copyright Eric Hunt.

Their dramatic appearance has made slipper orchids highly prized in cultivation or by flower collectors. Unfortunately, many species have been subject to over-collection as a result. Many of the temperate Cypripedium species now require intensive conservation management, and populations of some Paphiopedilum species have been driven close to extinction. Once again, it would be a tragedy if such a fascinating group of plants was to vanish from the world.

REFERENCES

Cox, A. V., A. M. Pridgeon, V. A. Albert & M. W. Chase. 1997. Phylogenetics of the slipper orchids (Cypripedioideae, Orchidaceae): nuclear rDNA ITS sequences. Plant Systematics and Evolution 208: 197–223.

Pemberton, R. W. 2013. Pollination of slipper orchids (Cypripedioideae): a review. Lankesteriana 13 (1–2): 65–73.

Rosso, S. W. 1966. The vegetative anatomy of the Cypripedioideae (Orchidaceae). Journal of the Linnean Society, Botany 59: 309–341.

A Spoonful of Lemba

Lemba or hill coconut Curculigo latifolia, from here.

The south-east Asian plant known as lemba has been referred to briefly on this site before, as a member of the family Hypoxidaceae. As noted in that post, it has been through a couple of names over the years: some sources will refer to it as Molineria latifolia, while others will call it Curculigo latifolia. The genera Molineria and Curculigo have been distinguished based on the presence of beaked (Curculigo) or unbeaked (Molineria) fruits and seeds, but the phylogenetic analysis of Hypoxidaceae by Kocyan et al. (2011) did not find this character to correlate with phylogeny. They therefore proposed to stop recognising the two genera as distinct, merging all species under Curculigo.

Curculigo latifolia is one of the largest species in the Hypoxidaceae. It is mostly found growing in damp, shaded locations, and the long-petioled leaves coming from an erect central rhizome can be a metre in length. Its small yellow flowers are placed at the base of the plant, at ground level; this distinguishes this species from various large orchid species found in the same region that may also be referred to as 'lemba' (or 'lumbah', or some other spelling/linguistic variant). The flowers give rise to small white berries, about an inch in size, with a distinct beak.

Fruit cluster of Curculigo latifolia, from DQ Farm.

Uses of this plant were recently reviewed by Lim (2012). The leaves provide a strong, lightweight fibre that is used to make nets, rope and cloth. The roots are brewed to treat various illnesses. However, the feature of this plant that has received the most attention in recent years is the fruit. These are edible, and are said to taste a bit like a sweet cucumber. The reason they have aroused interest, though, is that after eating one, anything else eaten within the next ten minutes or so will also taste sweet. This effect has been traced to a protein in the fruit, variously called neoculin or curculin, that has been reported to have several hundreds times the sweetness relative to weight of sucrose. Curculin has consequently been proposed as a potential low-calorie sweetener (to which I say, I'm sure it can't possibly taste worse than stevia), though one limitation is that the protein becomes denatured at temperatures above fifty degrees and loses its sweetening properties. As yet, though, it doesn't look like lemba sweetener has made it onto the commercial market.

REFERENCES

Kocyan, A., D. A. Snijman, F. Forest, D. S. Devey, J. V. Freudenstein, J. Wiland-Szymańska, M. W. Chase & P. J. Rudall. 2011. Molecular phylogenetics of Hypoxidaceae—evidence from plastid DNA data and inferences on morphology and biogeography. Molecular Phylogenetics and Evolution 60 (1): 122-136.

Lim, T. K. 2012. Edible Medicinal and Non-Medicinal Plants, vol. 4. Fruits. Springer.

Lachenalia

Back in 2011, I presented you with a post on the southern African flowering bulb genus Ledebouria. In that post, I mentioned that Ledebouria was just one of a wide diversity of ornamental plants found in that part of the world.

Lachenalia elegans var. flava, from the Pacific Bulb Society.

Lachenalia, sometimes known as Cape cowslips, is a genus of over 100 species found in Namibia and South Africa. Most Lachenalia species sprout and flower in the winter. Lachenalia is not too distant a relative of Ledebouria—both are classified in the squill tribe Massonieae—and bears a distinct resemblance to the latter with its fleshy leaves that are often blotched with purple. Some species of Lachenalia share the geophyllous habit I described in the earlier post for some Ledebouria, with the leaves growing pressed closely to the ground. However, Lachenalia differs from Ledebouria in having flowers with well-developed bracts, and anthers arranged in two series. Also, while the scales of Ledebouria bulbs are often loose, though of Lachenalia bulbs are always tightly packed (Manning et al. 2004).

Lachenalia zebrina f. zebrina, photographed by Alan Horstmann.

Lachenalia species include some popular garden plants, to the extent that some are known as invasive weeds here in the Perth region. Nevertheless, a simple image search immediately shows why they are so popular. Varieties of this genus are available in reds, pinks, yellows, purples... One species, L. viridiflora, has flowers of a quite remarkable turqouise colour. Though revered in cultivation, L. viridiflora is critically endangered in the wild, with a range of only 19 km² in which it is threatened by grazing, housing development and (almost ironically) the collection of specimens for horticulture.

Lachenalia viridiflora, photographed by A. Harrower.

REFERENCE

Manning, J. C., P. Goldblatt & M. F. Fay. 2004. A revised generic synopsis of Hyacinthaceae in sub-Saharan Africa, based on molecular evidence, including new combinations and the new tribe Pseudoprospereae. Edinburgh Journal of Botany 60 (3): 533-568.

Star-Grass

Common star-grass Hypoxis hirsuta, photographed by Merel R. Black.

It does not require a great deal of insight to understand why the plant pictured above has acquired the vernacular names of 'star-grass' or 'gold-star'. This small native of North America is one of the few representatives in that region of the family Hypoxidaceae, a group of about 150 species of thin-leaved monocots that is most diverse in the Southern Hemisphere, particularly in Africa. Most Hypoxidaceae are small like the North American gold-star, though the Asian hill coconut Curculigo latifolia may be over a metre in height. All grow from underground corms or rhizomes. Their flowers have the typical monocot arrangement of three sepals and three petals, and are most commonly yellow to pink in colouration. They mostly produce little scent (some have a faint sweet scent), and usually attract pollinators by offering pollen as a reward. Some species are grown as ornamentals, but for the most part the Hypoxidaceae are not that significant economically. The tubers of the African potato Hypoxis hemerocallidea (which, despite its vernacular name, does not seem to be eaten as a vegetable per se) have been used to make a medicinal tea; it has become particularly widely used in recent years to supposedly alleviate the symptoms of HIV, but tests of its actual efficacy remain in progress.

Lemba or hill coconut Curculigo latifolia (previously Molineria latifola), photographed by Ahmad Fuad Morad.

Recent authors have recognised up to ten genera within the Hypoxidaceae, but a phylogenetic analysis of the family by Kocyan et al. (2011) lead them to suggest the reduction of that number to four or six, depending on how one might chose to deal with the position of Hypoxidia. This is a distinctive genus of two species found on the Seychelles. Flowers of Hypoxidia are a dark red-brown colour, and in contrast to the weak scent of other Hypoxidaceae they have a strong foetid odour that attracts flies as pollinators. Kocyan et al.'s phylogenetic analysis placed Hypoxidia as sister to the other species of Hypoxidaceae found on the Seychelles, Curculigo seychellensis, and the two together were placed as sister to a clade containing the remaining species of Curculigo (as well as species of Molineria, which Kocyan et al. suggested be synonymised with Curculigo). Curculigo species bear their flowers at the base of the plant; the ovary is actually found beneath the ground, with the corolla borne above the ground on an elongate tubular rostrum. This rostrum is particularly long in C. seychellensis, up to 12 cm. Curculigo seychellensis also has bifurcated leaves that make it look superficially like a palm seedling. It remains to be settled whether future authors will prefer to place C. seychellensis in its own new genus, or to sink Hypoxidia into Curculigo.

Pauridia capensis (previously Spiloxene capensis), photographed by Bob Rutemoeller.

The remaining Hypoxidaceae can be divided between the genera Hypoxis (containing Rhodohypoxis as a junior synonym), Empodium and Pauridia (containing Spiloxene and Saniella as synonyms, as well as some Australian species previously placed in Hypoxis). Members of the genera Empodium and Pauridia produce annual corms, while Hypoxis species have tuberous rhizomes. Empodium and Pauridia differ in features of the flowers and seeds (Kocyan et al. 2011). The two African Pauridia species previously classified as Saniella resemble Curculigo in having subterranean ovaries. It is perhaps unfortunate that the name Pauridia, previously restricted to two particularly small African species only a couple of centimetres in height, takes priority over Spiloxene, previously used for a larger group of about thirty species. But such are the vagaries of nomenclature, and that which we now call Pauridia capensis (Snijman & Kocyan 2013) will smell as... generally indifferent, actually, but it at least looks pretty specky.

REFERENCES

Kocyan, A., D. A. Snijman, F. Forest, D. S. Devey, J. V. Freudenstein, J. Wiland-Szymańska, M. W. Chase & P. J. Rudall. 2011. Molecular phylogenetics of Hypoxidaceae—evidence from plastid DNA data and inferences on morphology and biogeography. Molecular Phylogenetics and Evolution 60 (1): 122-136.

Snijman, D. A., & A. Kocyan. 2013. The genus Pauridia (Hypoxidaceae) amplified to include Hypoxis sect. Ianthe, Saniella and Spiloxene, with revised nomenclature and typification. Phytotaxa 116 (1): 19-33.

Patterns on a Squill

Violet squill Ledebouria socialis, photographed by Stan Shebs.

The south of Africa is one of the world's centres for botanical diversity. Home to an abundance of the floristically wierd and wonderful, you might be surprised to know just how many of your favourite garden plants (assuming that you have favourite garden plants) originate from that part of the world: proteas, leucadendrons, red-hot pokers (Kniphofia), freesias, agapanthus*... to name a few. The subject of today's post, the genus Ledebouria, is perhaps not one of the best known of the southern African contributions to horticulture, but it's none the less noteworthy.

*Well, personally, I'm not that fussed on agapanthus ('orrible weedy things), but a not insignificant number of people would disagree with me on that point.

Ledebouria revoluta, from here.

Ledebouria is a genus of the plant family Hyacinthaceae that also includes such familiar plants as hyacinths and bluebells, and within that family to a group known as squills. Like other members of the family, Ledebouria species are bulbiferous with developed leaves only present for part of the year. There are about forty or more species of Ledebouria in southern Africa, with outliers in Madagascar and India (Manning et al. 2004), though the number of species varies according to whether or not the genera Drimiopsis and Resnova are treated separately. Molecular analyses have tended to fail to distinguish the three genera, but morphological and combined analyses support their reciprocal monophyly (Lebatha et al. 2006). The Drimiopsis and Resnova species have more loosely packed leaves in the bulb than the species of Ledebouria sensu stricto (Lebatha et al. 2006) and are mostly woodland and forest species as opposed to the open-country Ledebouria (Manning et al. 2004).

Ledebouria marginata, from here.

Some species of Ledebouria have become popular as houseplants, not for their flowers which are reasonably modest, but for their leaves which are fleshy and marked with dark purple blotches and stripes. The number of leaves produced from one bulb at a time varies from up to twenty-five to only a single leaf in Ledebouria monophylla. Mature plants may be up to a metre tall in L. zebrina, down to only 3 mm high in L. galpinii (Venter 1993). The latter (as well L. monophylla) is one of a number of species in which the leaves grow tightly pressed to the ground, so despite the low height of the entire plant, the individual leaves are up to 80 mm long. In such species, the total number of leaves at a time is always low, never more than five. This growth habit is known as geophylly, and the reasons behind it remain uncertain. Geophyllous plants are generally found in areas with strongly seasonal yet regular rainfall (Esler et al. 1999). It has been suggested that the geophyllous habit protects against grazing animals or against CO₂ or water loss; alternatively (as favoured by Esler et al.), it may create a microclimate that affects the temperature of the leaves, either causing their temperature to remain low in the mornings (allowing dew to form on the leaves) and/or raising the temperature of the leaves during midday (allowing elevated rates of photosynthesis).

Leaves of Ledebouria ovatifolia ssp. scabrida, a geophyllous species, photographed by Connall Oosterbroek.

As already alluded to, most Ledebouria plants form flower spikes bearing only pale flowers, though many species may produce more than one spike in succession over a single growing season. Flowers are insect-pollinated by Lepidoptera and Hymenoptera. Fruits are dry capsules, and the seeds are dispersed short distances from the parent plant by wind (generally by being scattered from a waving spike) or water (mostly by falling rain). Some species form lateral bulblets, such as the aptly named Ledebouria socialis (see this page on L. socialis as a house plant), leading to the formation of colonies of plants connected by subterranean stolons up to 200 mm long. The largest recorded such colony, for a clone of L. cooperi, had a diameter of five meeters (Venter 1993).

REFERENCES

Esler, K. J., P. W. Rundel & P. Vorster. 1999. Biogeography of prostrate-leaved geophytes in semi-arid South Africa: hypotheses on functionality. Plant Ecology 142 (1-2): 105-120.

Lebatha, P., M. H. Buys & G. Stedje. 2006. Ledebouria, Resnova and Drimiopsis: a tale of three genera. Taxon 55 (3): 643-652.

Manning, J. C., P. Goldblatt & M. F. Fay. 2004. A revised generic synopsis of Hyacinthaceae in sub-Saharan Africa, based on molecular evidence, including new combinations and the new tribe Pseudoprospereae. Edinburgh Journal of Botany 60 (3): 533-568.

Venter, S. 1993. A revision of the genus Ledebouria Roth in South Africa. MSc thesis, University of Natal.

Most Unbelievable Organisms Evah!

Last week I asked for nominations for the title of Most Incredible Organism Ever. Thank you very much to those of you who responded with your selections. Some of them were organisms I'd already selected myself, some of you reminded me of amazing organisms that were even better than the ones that I'd considered*. Certainly, getting the list down to ten top nominations was not easy, and I'm sure anyone else would have chosen differently from myself. Allen Hazen pointed out that, strictly speaking, "incredible" means "inspires disbelief", and certainly some of the things I have lined up do exactly that.

*As an aside, something that never fails to amuse is looking up what Google search terms have brought people to Catalogue of Organisms. Trust me, "amazing organism" is bound to bring in the punters.

Honorable mentions should be given to those organisms that people nominated that I didn't end up using, because they're certainly all incredible. Allen Hazen suggested the platypus, while Alan nominated the aye-aye. Dave Coulter was all for the Osage orange, while Amie Roman asked me to "pick an onychophoran, any onychophoran".

But I'm afraid I ended up passing over these wonders. In no particular order, here are my nominations for "Most Incredible Organism" (click on the pictures to be taken to their source):



Homo sapiens Linnaeus, 1758: Both myself and Mike Keesey agreed on this one. As much as I hate to stoke this species' notoriously smug satisfaction, it has to be admitted that humans are pretty amazing. Douglas Adams once explained that "The History of every major Galactic Civilization tends to pass through three distinct and recognizable phases, those of Survival, Inquiry and Sophistication, otherwise known as the How, Why and Where phases. For instance, the first phase is characterized by the question How can we eat? the second by the question Why do we eat? and the third by the question Where shall we have lunch?" As far as we know, Homo sapiens is the only species on this planet to have reached Adam's second stage, let alone the third.



Polyascus polygenea (Lützen and Takahashi, 1997): Polyascus polygenea is a member of the Rhizocephala, notorious crustacean parasites of crabs. The larval rhizocephalan looks very similar to the larva of a barnacle (to which it is closely related), but when it finds a decapod host it burrows in and transforms into an almost fungus-like mass spreading through the hosts body. The only externally visible part of the parasite is its large egg-sac (the orange tube in the picture above, which does not show a Polyascus but another rhizocephalan species, Peltogaster paguri). The rhizocephalan egg-sac grows at the base of the crab's tail, where it would normally hold its own eggs. In order to make sure this spot is free, the rhizocephalan chemically castrates its host, preventing it from ever reproducing. It also affects its host's behaviour so that the crab lovingly tends the parasite's egg-sac as if it were its own. So powerful is the parasite's mental ju-ju that even male hosts that would not naturally produce eggs will tend the parasite just as a female would.

Vasha nominated the best-known rhizocephalan, Sacculina carcini, but I've decided to go with Polyascus polygenea because this species adds a further twist to the tale. A single Sacculina larva will give rise to a single egg-sac. But Polyascus reproduces within the host asexually by budding, so that one larva will give rise to multiple egg-sacs (Glenner et al., 2003).

Polyascus is also acting as the stand-in for all mind-controlling parasites. As we learn more about the natural history of parasitic organisms, it turns out that behavioral control of parasites over their hosts is not uncommon. Parasitic wasps make caterpillars guard the wasp's cocoons. Horsehair worms make crickets drown themselves so the aquatic adult worm can emerge. Tanya reminded me about Cordyceps unilateralis, a fungal parasite of ants that, when it's ready to produce spores, makes its host climb to the highest available point so that the spores will spread as far as possible. The ways of parasites are disturbing. And speaking of disturbing...



Acarophenax tribolii Newstead & Duvall, 1918: It is not uncommon for pregnant women to express delight at feeling their baby kick inside them. But what if it was doing more than just kicking? Mites of the genus Acarophenax are parasites of beetles that can claim to have perhaps the just-plain-ickiest life history of any animal. The sex ratio of this genus is highly skewed - depending on the species, a brood may contain up to thirty females, but usually only a single male. These offspring reach sexual maturity before they are even born, and the male proceeds to fertilise all of his sisters while still within their mother. In fact, the male doesn't even survive to become free-living - by the time the already-fertilised females emerge from their parent, the male has reached the end of his short (but extremely busy) lifespan. The advantage to the mite in this twisted incestuous life cycle? An exceedingly short generation time, of course - Acarophenax mahunkai, for instance, has a generation time of only three to five days (Steinkraus & Cross, 1993).



Mites of the closely related family Pyemotidae have a similar life cycle - the offspring reach full sexual maturity while in their mother, and begin copulating the instant that they emerge from their proud parent. Females of Pyemotes herfsi (shown in the picture above), known as "itch mites" and facultative biters of humans, can produce more than 250 fully mature offspring.



Welwitschia mirabilis Hook.f.: I also have to thank Tanya for reminding me of the wonder that is Welwitschia. Welwitschia mirabilis is unique to the Namib Desert in Angola and Namibia, and is a member of the gymnosperm order Gnetales along with the genera Ephedra and Gnetum. The Gnetales have received a lot of attention due to their much-debated phylogeny (morphological characters suggest they are the living sister group to angiosperms, while molecular analyses place them closer to conifers), but that's not what's so amazing about Welwitschia. It's not even the bright pink, insect-pollinated cones. What makes this plant so incredible is the way it grows. Welwitschia mirabilis only ever produces two adult leaves, followed by the death of the plant's apical meristem (growing tip). The two strap-like leaves, however, continue to grow indefinitely, and can reach lengths of over eight metres (most individuals look like they have more than two leaves, but this is only because of the leaves splitting as the ends get frayed). Welwitschia is very slow-growing, and individual specimens can live to be hundreds, if not thousands of years old.



Argentinosaurus huinculensis Bonaparte & Coria, 1993: There's no other way to say it - sauropods were just stupidly huge. And Argentinosaurus was one of the most ridiculous of all, being the largest well-characterised sauropod (potentially outdone only by such almost-apocryphal taxa as Amphicoelias fragillimus and Bruhathkayosaurus matleyi). With an estimated total length of nearly thirty metres, and potential weight of up to 80 tonnes... well, there's nothing much that can be said in response except "Whoa".

Sauropods are so huge that when a popular blog was set up dedicated to them, the site authors couldn't fit in the entire animal and were forced to dedicate themselves to a single section. I refer, of course, to the famed Sauropod Vertebra Picture Of the Week - SV-POW!. Rumour has it, however, that a second site is in the works devoted to sauropod crania, to be called "Sauropod Heads - Anatomy, Zoology And Morphology".



Rhizanthella slateri (Rupp) M. A. Clem. & P. J. Cribb, 1984: Rhizanthella is a small genus of three orchid species unique to Australia. What makes Rhizanthella so amazing is that its entire life cycle is spent underground. The plant is saprophytic, dependent on an associated fungus for nutrition, and its stems are entirely subterrean. Even the flowers do not have to break the surface - they are pollinated by minute gnats that can reach them through tiny cracks in the covering litter. The first known Rhizanthella specimens were discovered in 1928 when they were brought up by a farmer's plough, and only intermittent finds were made for a long time afterwards. Even today, their obscure habits mean that Rhizanthella species are poorly known. Sad to say, they are also all regarded as endangered. They are only known from restricted, scattered ranges, limited by the presence of their associated fungus and the tree of which it is in turn connected to mycorrhizally (in Rhizanthella gardneri, the tree is Melaleuca uncinata, but the associations of Rhizanthella slateri are still unknown).

Vasha reminded me of Rhizanthella by telling me of the American saprophytic plant Thismia americana, which also spends most of its life underground with only the minute flowers emerging above the surface. Thismia americana has not been recorded since 1916, and is feared to be extinct, though it is hard to know for certain. As described at the link, an intensive search in the early 1990s failed to find any specimens, but a concurrent dummy run using scattered white beads about the same size as T. americana flowers was also a failure.



Puccinia monoica Arthur, 1912: The object of the photo above is not a flower. It grew from a flowering plant, but it's not a flower. Puccinia monoica is a fungus parasitic on Brassicaceae (mustard) species. Like rhizocephalans on their crabs, Puccinia monoica changes the reproductive biology of its host, preventing it from growing its own flowers. Instead, it makes the host plant grow a tight whorl of leaves, which are covered by the bright yellow sporangia of the fungus. Not only does the fungus-induced 'false flower' look like a real flower, it even produces nectar and scent like a real flower, attracting insect pollinators just like a real flower would (Raguso & Roy, 1998). And just like pollen from a real flower, these pollinators carry spores from fungus to fungus, cross-fertilising the fungi as they do so.



Deinococcus radiodurans (ex Raj et al. 1960) Brooks and Murray 1981: A dose of radiation of 10 joules per kilogram will kill a human being. Sixty joules per kilogram will kill Escherichia coli. Deinococcus radiodurans may look like a fairly unremarkable bacterium at first glance, but it can withstand a radiactive dose of 5000 joules per kilogram and not even blink (that is, if it had eyes they wouldn't blink). It can withstand radiation so strong that its genome is simply blasted to pieces, stoically knitting the fragments back together again afterwards. Deinococcus can withstand extreme heat, extreme cold, and strong acidity. In a pun so bad that it demands to be repeated, this organism has been dubbed Conan the Bacterium. Pavlov et al. (2006) went so far as to suggest that Deinococcus' incredible resilience to radiation indicated an extraterrestrial origin, carried from Mars on an asteroid, but it seems more likely to be a by-product of resilience to other stressors such as desiccation (Cox & Battista, 2005). Still, one can't help wondering if, even if it didn't come from Mars in the first place, it has managed to make it over there on one of Earth's probes.

So resistant is Deinococcus to everything possibly imaginable, in fact, that we still have no idea where it lives naturally. It was first isolated from cans of irradiated beef, and has not yet been found to be abundant in any particular environment. Phylogenetically, Deinococcus forms a clade with the thermophilic bacterium Thermus (one species of which, Thermus aquaticus, is of enormous significance to molecular biology as the source of the Taq enzyme used in PCR). This clade is most commonly referred to (rather unimaginatively) as the Deinococcus-Thermus group, but I personally prefer the name given to them by Cavalier-Smith (2002) - Hadobacteria, the bacteria of Hades.



Proteus anguinus anguinus Laurenti, 1768: The white olm, the only truly cave-dwelling tetrapod (the closely related black olm, Proteus anguinus parkelj, is a surface-dweller). [Update: Much to my chagrinn, Nick Sly has reminded me that there are other cave-dwelling salamanders out there.] I've included the olm not only for its own sake, but as a representative of the entire world of troglobitic and stygobitic fauna (troglobitic animals are those that live in actual caves while stygobitic taxa live buried in the ground, usually in aquifers). In this strange, silent world, animals are almost entirely dependent on food particles washing down from the surface, so life underground is slow, and patient. Troglobites can go for incredible amounts of time without eating - Darren Naish informs us of an olm that was supposedly kept at the Faculty of Biotechnology in Ljubljana without food for twelve years! If that is what a large, complex vertebrate is capable of, imagine what is possible for the smaller invertebrates with their lower metabolic requirements.

And last, but certainly not least:



Wasmannia auropunctata (Roger, 1863): Commonly known as the little fire ant or electric ant (the latter name has been promoted in recent years to dissuade confusion with the larger, not closely related fire ants of the genus Solenopsis), Wasmannia auropunctata is regarded as one of the world's worst invasive organisms. It has been linked with decreases in biodiversity in locations to which it has been introduced, and has a painful sting to boot. It also has one of the world's most remarkable reproductive systems (Fournier et al., 2005). Like other ants, Wasmannia has both haploid males and diploid females, with the females divided between reproductive queens and non-reproductive workers. Genetically, though, Wasmannia is a little different from other ants. While males appear to mate with queens the normal way, only workers are produced by male fertilisation. Any new queens that are produced are genetically identical to their mothers. Still, the male lineage doesn't disappear - somehow, the male genes are able to eliminate the female genes from some of the eggs, and the resulting male Wasmannia are genetically identical to their fathers.

Wasmannia is one of very few organisms that exhibit androgenesis - clonally reproducing males. The only other known natural habitual cases are a cypress species, Cupressus dupreziana, and freshwater bivalves in the genus Corbicula, though odd cases of androgenesis have been recorded in laboratory and cultivated organisms (Hedtke et al., 2008). Effectively, the male and female Wasmannia are reproductively isolated from each other - they are separate species.

REFERENCES

Cox, M. M., & J. R. Battista. 2005. Deinococcus radiodurans — the consummate survivor. Nature Reviews: Microbiology 3 (11): 882–892.

Fournier, D., A. Estoup, J. Orivel, J. Foucaud, H. Jourdan, J. Le Breton & L. Keller. 2005. Clonal reproduction by males and females in the little fire ant. Nature 435: 1230-1234.

Glenner, H., J. Lützen & T. Takahashi. 2003. Molecular and morphological evidence for a monophyletic clade of asexually reproducing Rhizocephala: Polyascus, new genus (Cirripedia). Journal of Crustacean Biology 23: 548-557.

Hedtke, S. M., K. Stanger-Hall, R. J. Baker & D. M. Hillis. 2008. All-male asexuality: origin and maintenance of androgenesis in the Asian clam Corbicula. Evolution 62 (5): 1119-1136.

Pavlov, A. K., V. L. Kalinin, A. N. Konstantinov, V. N. Shelegedin & A. A. Pavlov. 2006. Was Earth ever infected by martian biota? Clues from radioresistant bacteria. Astrobiology 6 (6): 911-918.

Raguso, R. A., & B. A. Roy. 1998. 'Floral' scent production by Puccinia rust fungi that mimic flowers. Molecular Ecology 7 (9): 1127-1136.

Steinkraus, D. C, & E. A. Cross. 1993. Description and life history of Acarophenax mahunkai, n. sp. (Acari, Tarsonemina: Acarophenacidae), an egg parasite of the lesser mealworm (Coleoptera: Tenebrionidae). Annals of the Entomological Society of America 86 (3): 239-249.

There's Treasure Everywhere

I've whinged about it multiple times in the past (see here and here), but the number one misunderstanding that most people seem to have about biodiversity is how much we know about it. Only a relatively small fraction - possibly less than 10% - of the world's species have been described. Corrolary to that is the idea that new species are only discovered in exotic, far-off lands, wonders of darkest Africa and hidden Himalayan Shangri-La. Well yes, doubtless those places do harbour their fair share of undescribed species, but sometimes new species can be discovered right on civilisation's doorstep (by which, being the parochial types we are, we mean Western civilisation, of course).

ArtPlantae Today has a story about a new plant species discovered in California, Brodiaea santarosae (the photo at the top of the post is of a different Brodiaea species, B. californica ssp. leptandra, and comes from Wikipedia). An information page here gives more info on the plant, as well as a link to the actual published paper. It also mentions the tragically interesting fact that B. santarosae is restricted to a basalt soil that has mostly been removed by (natural) erosion, with only some three percent of its area left. With continued erosion, the basalt soil might be expected to disappear within the next 100,000 years or so, carrying the habitat of this new species with it. [Hat-tip to Seeds Aside]

Even more amazing, I hear from Benny Bleiman that not one, not two, not even three, but no less than 57 new species of fish have been identified in a survey of Europe! Benny has the audacity to call this discovery boring, but the idea that there could be so many species yet to be discovered in the very continent that invented the whole concept of scientific taxonomy is just completely mind-blowing!

It's a magical world.

REFERENCES

Chester, T., W. Armstrong & K. Madore. 2007. Brodiaea santarosae (Themidaceae), a new rare species from the Santa Rosa Basalt area of the Santa Ana Mountains of southern California. Madroño 54 (2): 187-198.