Field of Science

Friday Fabulous "Flower" - Euphorbia

As the days lengthen and the sunlight heats up the greenhouse, a lot of our tropical plants begin to flower. This is Euphorbia splendens and as the name suggests it is a pretty spectacular plant, with a cluster of spiny stems terminated by a helical whorl of leaves and very showy clusters of "flowers". This plant grew in the miserable little excuse for a greenhouse that was at my undergraduate college, and a particularly perverse botanist (Aren't they all a bit perverse?) let a pair of us struggle all afternoon to identify the family knowing full well we were making a fundamental mental error. Yes, we kept trying to sort out the flower's parts and nothing made any sense because the key separated out plants with milky sap without regard to flowers, and this plant readily oozes latex, and if we'd paid attention it all would have made sense. The flowers in this genus and family are small and unisexual, and in plants like this a number of flowers are clustered together into an inflorescence surrounded by a pair of very showy bracts. So those aren't petals or perianth at all, and the number of flowers per cluster isn't constant, so it seems you have different numbers of pistils and stamens. But did the Phactor ever forget this lesson? No, you only get to fool me once.


Lee said...

Oh.... I thought E. splendens was a synonym of E. milii var. splendens.... perhaps I'm wrong?

The Phytophactor said...

It may very well be var. splendens. The ultimate authority from my perspective was simply the pot label that has been unchanged for 30 years or so. Greenhouse taxonomic revisions come slowly if at all, but there is a certain comfort in the stability.

Unknown said...

It nearly always IS E. milii var. splendens in cultivation. The true E. milii is a much "smaller in all parts" version with smaller, less showy bracts and weedier looking stems. Recent horticultural developments in Thailand have produced the even showier 'Poysean Hybrids' which are quite stunning. Details of the species involved are sketchy, but I suspect the primary candidates are E. milii of one sort or another, along with an admixture of E. leuconeura. Polyploidy might also be involved, given that the hybrids are much more robust plants with giant bracts. They also come in a lot of "floral" colours - deep reds, pinks, yellow, peach cream and white are all out there.

Taxonomically speaking, E. splendens and E. milii are very old names, being first given to these plants in the 1820s. E. splendens was reduced to a variety of E. milii in 1955. The details according to Plant List are "Euphorbia milii var. splendens (Bojer ex Hook.) Ursch & Leandri is an accepted name

This name is the accepted name of an infraspecific taxon in the genus Euphorbia (family Euphorbiaceae).

The record derives from WCSP which reports it as an accepted name (record 80899) with original publication details: Mém. Inst. Sci. Madagascar, Sér. B, Biol. Vég. 5: 148 1954 publ. 1955."

Oddly, this particular listing doesn't seem to appear in IPNI, which surprised me somewhat. If I get 5 minutes, I'll fire them off an e-mail on the subject.

Ciao, KK.