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XLI.—REVISION OF THE GENUS DICOMA. 
F. C. Witson. 
The generic name Dicoma was first mentioned by Cassini in 
1817* in his account of the tribe Carlineae, and the type species, 
D. tomentosa, was described by him in 1818?. He published a 
further description of the genus and species in 1819?. 
Lessing, in his account of the Compositae of the Berlin Her- 
barium in 18304, added five new species, and arranged them in 
three sections, founded on characters derived mainly from the 
pappus, as follows :— 
peeb.. 1. D. ne aig D. capensis. 
Sect. II. D. 1 
Sect. III. D. Dunucstie D, diacanthoides, D. Burmannii. 
Two years later Lessing® raised these sections to subgeneric 
rank as follows:—I. Leucophyton. Il. Rhigiothamnus. III. 
Macledium. 
De Candolle® in 1838 enumerated ten species, slightly re- 
arranging the groups and splitting Lessing’s Leucophyton into 
two parts, Hudicoma and Steirocoma, and he added a fifth, 
Pterocoma, which included D. speciosa. 
In 1864-5 Harvey’ gave descriptions of eleven species from 
South Africa, arranged more or less after De Candolle, whilst in 
1877 Oliver and Hiern® recorded four species from Tropical 
Africa. 
In the following revision I have found it convenient to divide 
the 34 species now known into three sections 
I. Dimorphae.—Pappus snmeaiiniac the outer setae 
barbellate or very rarely those of the outer 
flowers uniform and plumose (D. capensis), 
it inner setae broader with more or less 
mbranous margins. 
II. Barbellatae. seed a tee not dimorphous, all the setae 
rbellat 
fii, Phorhsnde Pe apis not dimorphous, all the setae 
plumose. 
The following Revision is compiled from an examination of 
the material in the herbaria of the Royal Botanic Gardens, apt 
and the Natural History Museum, South Kensington. 
also indebted to Archdeacon Rogers for placing the specimens eon 
his herbarium at my disposal. 
Key TO THE SPECIES. 
Section I. DimorpHaz. 
Pappus of all the flowers barbe late 
Leaves glabrescent or scabrid pest with 
1 Dict. Sci. Nat., 7: fel 2 Bull. Soc. Philom. 12; * Dict. Sei. oe 13: 
sete aaa ea 5: 276; ® Synop. nr eae 109; ®Prodromus 7: 35; 
7 Fl. Cap. 3: 516; § Fl. Trop. Afr. 3: 
