1963] 



BOTANY OF THE GUAYANA HIGHLANDS PART V 



237 



mit, elsewhere irregularly short setulose or papillate short-hirtellous on the 

 surface, but definitely not glabrous as illustrated by Poeppig & Endlicher nor 

 described as such by Schumann or by Gleason & Standley. The seeds in the 

 Poeppig & Endlicher collection are immature and rather flattened, but under 

 high magnification a characteristic lineolate surface is faintly revealed. The 

 Schomburgk 968 specimen, cited by Schumann under P. dichotoma, likewise 

 shows the hypanthium to be hispidulo-setulose at the summit and elsewhere 

 below shortly hispidulous. 



Moreover, the holotype and isotype specimens, together with the paratypes 

 of P. scaposa Gleason & Standley. show the same type of hispidulous hypanthium 

 and transversely lineolate seeds as in P. dichotoma. In fact, a critical study of 

 herbarium material of these two taxa does not reveal any differences whatsoever 

 as regards the surface markings of the seeds or their angulate character nor the 

 hispidulous surface of the hypanthium. The two taxa, therefore, cannot be sepa- 

 rated on the basis of the characters used by Gleason and Standley. However, one 

 difference — that of the matter of the relative density and length of the hairs 

 on the lower surface of the leaf -blade— does emerge to become the chief and only 

 criterion for distinguishing the two taxa. Although there is some intergradation 

 in this character, resulting in several intergrading specimens, most of the material 

 can be segregated on this basis. The most widespread variation is typical var. 

 dichotoma, in which the hairs along the nerves of the lower surface are loosely 

 spreading and fairly conspicuous, varying in length mainly from (0.75)1-2 mm 

 long. In the material of var. scaposa, on the other hand, the hairs along the nerves 

 of the lower surface are either absent or minute, more or less appressed, and 

 inconspicuous, varying chiefly from 0.1-0.5 mm, rarely up to 1 mm long. In both 

 varieties the upper surface of the leaf is usually densely villous or hirsutulous, 

 the var. scaposa tending to have usually relatively shorter and fewer hairs than 

 in var. dichotoma, although there is much intergradation. In one variation, var. 

 hirsutula, both surfaces of the leaves are densely hirsutulous, the hairs on the 

 lower surface completely hiding the main nerves. Specimens which are inter- 

 mediate between var. dichotoma and var. scaposa are Cardona 883, Killip 37356, 

 Steyermark 58166, Maguire & Fanshawe 23211, Maguire, Cowan, & Wurdack 

 30654 and 29744, Maguire & Maguire, Jr. 29081, and Maguire & Politi 28032. 

 These specimens show intergrading lengths and density of indument along the 

 nerves of the lower leaf surface. It is possible that the var. scaposa may eventually 

 have to be united with var. dichotoma. This may await more detailed field ob- 

 servations and breeding and transplanting experiments. 



Individual plants, as well as local colonies, are sometimes encountered with 

 the pairs of lower leaves separated by elongated internodes 0.5-4 cm long and/or 

 with larger leaves 4-5 cm long and 1.6-2.7 cm broad. This type of variation with 

 large leaves and elongated internodes is represented by the collection of Maguire, 

 Steyermark, c(; Maguire 53621 (cited above), whereas the elongated internode 

 variation with smaller leaves may be noted in the collection of Maguire, Steyer- 

 mark, & Maguire 53548. In the latter, the leaves are both rosulate as well as on 

 elongated internodes, whereas in the former (no. 53621), all the individuals of the 

 local colony exhibited the comparatively larger leaf blades of 4-5 cm in length. 



With its rosettes of leaves which are often lavender below and the little heads 

 of white to blue or lavender-blue corollas, the plants of this taxon are delicately 

 beautiful subjects, which lend themselves as interesting herbaceous material for 

 rock gardens and garden beds. They are characteristic of the upper slopes and 

 summits of the sandstone table mountains throughout southern Venezuela, ascend- 



