Julian Slade julian_slade@bigpond.com
Thu, 05 Dec 2002 22:50:52 PST
Dear all

There is a lot of current controversy around the limits of the genus
Ornithogalum (also for Drimia and Scilla) following DNA sequence analysis by
M. Pfosser & F. Speta published in Annals of the Missouri Botanical Garden,
86: 852-875 (1999).

The sequence data indicate that Ornithogalum and Albuca are mixed up with
each other; a situation is similar for the Drimia/Urginea group as well as
for Scilla and relatives. For this note, I'll stick to Ornithogalum.

Basically, Pfosser & Speta argue that these genera must be divided into
smaller ones for any sense to be made of the DNA results. These smaller
genera can generally be distinguished by seed structure, a characteristic
previously underestimated. These smaller genera are:

Eliokarmos: O. thyrsoides, O. dubium, etc. and relatives;
Melomphis: O. arabicum and relatives;
Cathissa: O. reverchonii and relatives;
Loncomelos: O. pyrenaicum, O. arcuatum, etc. and relatives;
Honorius: O. nutans and relatives;
Ornithogalum: O. umbellatum and relatives;
Zahariadia: O. saundersiae, possibly also O. xanthochlorum;
Ornithogalum juncifolium, not allocated a 'new' genus name, also formed a
separate group.

The green-flowered species of Galtonia were found to be most related to
Zahariadia. The only other Galtonia, the white G. candicans, was closer to
the following group centered around Albuca:

Stellarioides: O. longibracteatum and relatives;
Coilonox: O. secundum, O. suaveolens and relatives;
Albuca: unchanged
A rare species of Ornithogalum, O. etesiogaripense, formed another group;
this group would presumably comprise O. unifolium and relatives.

There are 2 ways to interpret these results: either smaller genera must be
recognised, or part of Ornithogalum must be transferred to Albuca. The
latter approach, in my opinion, will result in super-genera each of which do
not appear to have defining features.

I would welcome any comments from professional botanists who are aware of
this research.

I hope that this does not confuse you all, but at least you will be warned
of some changes in store!


Julian Slade

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