Tuesday, 8 March 2016

Frosty leaf a misnomer but neohymenopogon apt


I try not to proselytise on behalf of botanical names and their derivations. I find nomenclature interesting because I'm a taxonomist and that's part of what we do, but it feels like a lazy way to generate a story. Sometimes, though, you just have to ask what's going on with a name.

A case in point is Neohymenopogon parasticus, a generously flowering epiphyte from China and thereabouts. In January we had one in full bloom in the nursery and one just finishing up in the Southern Chinese collection beside the Ornamental Lake.


Starting at the start, neo means 'new'. Hymen is a membrane of some kind, as most of us know. Pogon is a beard, as in Leucopogon, the Australian heaths with hairy petals. So, all up, the new membranous beard.

Now, often 'neo' is added to another name to designate a group of plants a bit like another, or perhaps in a new area, or sometimes to simply fix up a 'bad' name (that is, one that has some technical problems and can't be used). So this genus might be a bit like something called Hymenopogon, or it might be what used to be called Hymenopogon but can no longer be done so.

It seems to be the latter. When Nathaniel Wallich gave this plant the name Hymenopogon in 1824 he was apparently unaware of the same name, more or less (Hymenopogum), being used in 1816 for a moss. Because we taxonomists agree that who so ever names a plant first is to be respected and their name treasured for all time, that name or its 'orthographic' variant must remain attached to the moss.

In 1981 this problem was fixed by Sigamony Bennet, by publishing the new name with a new beginning about newness... Neohymenopogon. So that bit's sorted. As to the membranous beard, that I expect refers to the hairy petals you can see in these pictures.


The species name is pretty obviously suggesting it's a parasite. That is, it lives off another organism by some means. I don't think our plant really is a parasite and certainly we grow it without any host. However it might be a reference to where it grows in nature, often attached to trees above the ground. 

This species (see even I want to avoid using that elongated name) is in the large, mostly tropical plant family Rubiaceae, diagnosed generally by the pairs of leaves with tiny pennants (called stipules) between them. You can't see much of that in these pictures but the occasional frost-covered leaf is pretty cool.


This distinctive foliage is found below a clusters of flowers, and (other) botanists describe it as a petaloid bract. In this case it hasn't made much of an effort to look like a petal, apart from matching the colour, so perhaps a better name would be a foliaceous bract. Similar leaf-like appendages adorn the flowers of other plants, such as the four species of another tongue-twisting genus, Schizophragma, a climbing Hydrangea relative from the same parts of the world (we have a Japanese species, Schizophragma hydrangeoides, growing between the Rose Pavilion and the Ornamental Lake).

There are three species of Neohymenopogon, but only parasiticus grown in Melbourne Gardens. It was discovered and described by Nathaniel from the Himalaya in India but its natural range extends into China. The other two species also come from the Himalaya region. While Neohymenopogon parasiticus only occurs down to 1200 metres above sea level in its native habitat, it seems happy enough at ground level here in Melbourne, not requiring mountains or a plant host to hoist it skywards.

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