SCHOMBURGK’S GUIANA PLANTS. 289 
same character, the deciduous lobes of the calyx. | In Osbeckia . 
the calyx is usually more or less covered with palmate or 
stellate hairs or appendages, and the stamens are smooth ; in 
Pleroma, the hairs or bristles of the calyx are equally simple, 
and the filaments more or less hairy, but neither of these 
characters is constant. In habit, Osbeckia agrees rather with 
Some sections of Chetogastra, and as in that genus the flowers 
are sometimes 4-merous, sometimes 5-merous; but the Os- 
beckia canescens;( E. Mey.) appears really to be nearer Ple- 
roma than Osbeckia, although a native of South-East Africa. 
There are no Pleromas in the Guiana collections before 
me; but among my Brazilian ones I observe nos. 33, 40,398, . 
403, 404, 406 to 412, and 1603 of Gardner, and n. 269 of 
Blanchet, and n. 1272 of Mathews from Peru. 
~ Tibouchina is intermediate between Pleroma and Cheto- 
gastra, to the former of which Chamisso unites it. All the 
Species are covered with thick rigid appressed sete ; the habit 
is that of some Chetogastre; the limb of the calyx is almost — 
Persistent ; and the bracts are persistent, which never occurs 
in Pleroma, whilst the stamens are often hairy as in that 
genus. Besides Aublet’s species, : Mathews _n. 1267, and 
two or three Brazilian ones belong to this genus. 
r T OA facia lag E A, T 
and perhaps Centradenia, (Don), or Plagiophyllum (Schlecht.) 
and Herria, (Schlecht.), may be divided into several natural 
Sections, some of which might be perhaps conveniently con- 
Sidered as genera; but for this purpose it does not appear 
oe number of parts can be used, which has been doneby ` 
De Candolle and by Chamisso. My materials are not at 
Present sufficient to satisfy me as to the number or the 
limits of these sections; but it appears to me that Arthro- 
stemma campanularis should be associated with Chetogastra 
stricta, echinata, cernua, conferta, and other stiff Peruvian 
shrubby species with pendulous. flowers; that the greater 
| number of De Candolle’s ; gum anth Mine Pome form 
(Puts of ihe section Z adano psis; wat Chetogastra a aricate ( 
Vol IL.—No. 14. gr 
