DESCRIPTIONS OF THE SPECIES 
259 
Sori two to four lines long in the specimens seen, placed on 
the side of the segment, and absent from its rounded apex. 
Involucre rather wide. Texture of frond thin. Mid-rib has 
a green scale at the base of each pinnule, on the upper surface. 
Very similar but apparently quite distinct from P. biaurita. 
This belongs to the section Tripartitae, in which the 
lowest pinnae are much larger than the others, often nearly 
equalling the central portion of the tripinnate frond. 
In dealing with P. longipes D. Don, Baker states (“ New 
Ferns,” Annals of Botany, Vol. V, 1891): “Further material 
shows P. brevisora Baker (No. 39, Syn. Fill), which has now 
been found in Zambesia, to be only a variety of this species 
with shorter sori.” But Christensen maintains P. longipes 
D. Don from tropical Asia, and P. brevisora Bkr from West 
tropical Africa. 
P. brevisora. Baker, Syn. Fil. 162, 1867; C. Chr. Index , 594. 
Rhodesia. — Common in forest; Chirinda Forest, 3700 to 4000 ft alt., 
June 1906 (Swynnerton, 854, 871). 
146. Pteris Buchanani Sim. 
Plate 130. Upper side of lower pinna, nat. size. 
Rhizome creeping. Fronds two to three-pinnate, glabrous, 
two to four feet long, one and a half to three feet broad, more 
or less tripartite, on a stipe one to three feet long. Pinnae 
stalked, numerous, lanceolate, and cut nearly, but not quite 
to the rachis, into linear pinnules, one to two inches long, 
two lines broad, sharply toothed where not fertile, and not 
narrower where fertile than above. Lower pinnae much the 
largest, having several pinnate pinnae on each side, but largest 
on the lower side. Lower pinnules sometimes distinct, and 
again pinnatifid or lobed ; others more or less connected 
along the mid-rib, so that the lower veinlets, of one pinnule 
unite with those of its neighbours, forming regular areolae 
along the mid-rib. Texture herbaceous; colour green. In- 
volucre half line broad, white and membranaceous, distinctly 
intramarginal, not reaching the point of the pinnules. In 
young plants the anastomosing venation is quite distinct, 
and the frond is roundly, five-lobed, or three-partite in 
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