522 
PENNISETUM 
Pennisetum Rich. Gramineae (v). 40 sp. trop. and subtrop. Afr., S. 
Eur., As., Am. Involucre as in Cenchrus. P. typhoideum Rich., the 
bulrush, spiked, or pearl millet, is extensively cult, in India. 
Pentachaeta Nutt. Compositae (111). 6 sp. Calif. 
Fentaclethra Benth. Leguminosae (1. 6). 2 sp. trop. Am. and Afr. 
Pentadesma Sabine. Guttiferae (vi). 1 sp., P. butyracea Sabine, the 
tallow or butter tree, in Sierra Leone. The fruit yields a greasy juice 
used as butter. 
Pentapetes Linn. Sterculiaceae. 1 sp. Indo-mal. 
Pentaphylacaceae. Dicotyledons (Archichl. Sapindales). A small 
order comprising the genus Pentaphylax, formerly placed in Theaceae. 
See Nat . PJi . for details. 
Pentaphylax Gardn. et Champ. Pentaphylacaceae. 1 sp. Hong-kong. 
Pentapterygium Klotzsch. Ericaceae (in. 8). 5 sp. E. Himal. to 
Khasia. Fruit a five- winged berry. 
Pentarhaphia Lindl. Gesneraceae (11). 15 sp. trop. Am., W. Ind. 
Pentas Benth. Rubiaceae (1. 2). 10 sp. Afr., Madag. 
Penthorum Gronov. ex Linn. Crassulaceae. 1 sp. N.E. Am., Chi., 
Japan. 
Pentstemon Mitch. Scrophulariaceae (11. 6). 80 sp. N. Am., E. As. 
Several sp. are cultivated. The posterior sta. is represented by a 
large staminode which is bent down and lies upon the lower side of 
the corolla, out of the way of insect- visitors (cf. Scrophularia). 
Pentzia Thunb. Compositae (vn). 10 sp. S. Afr. 
Peperomia Ruiz et Pav. Piperaceae. 400 sp. trop., esp. Am. Many 
are epiphytes with creeping stems, adventitious roots and fleshy leaves 
(water-tissue under the upper epidermis, see pp. 167, 175). Firs. 2 , 
with 2 sta., arranged in terminal spikes, which may, as in Piper, give 
rise to a sympodium. (See Ann. Bot. xx. p. 395, and xxi. p. 139.) 
Peplis Linn. Lythraceae. 3 sp. wet places, N. temp. P, Portula L. 
occurs in Brit. It is a little annual herb, very like Montia fontana 
with minute hexamerous firs. Self-fertilisation occurs by the bend- 
ing inwards of the sta. over the stigma. The fruit is bilocular (the 
partition does not come up to the very apex) with many seeds, but 
indehiscent. When submerged the plant has a more etiolated structure 
and becomes perennial. 
Pera Mutis. Euphorbiaceae (A. 11. 2). 25 sp. trop. Am. 
Perebea Aubl. Moraceae (11). 10 sp. trop. Am. 
Pereskia Plum, ex Linn. Cactaceae (ill). 13 sp. trop. Am., W. Ind. 
Leafy plants (see order). Some, e.g. P. aculeata Mill., climb like 
Rubus w T ith recurved thorns. 
Perezia Lag. Compositae (xn). 70 sp. Texas to Patagonia. 
Pergularia Linn. Asclepiadaceae (11. 4). 10 sp. Afr. and trop. As. 
Pericopsis Thw. Leguminosae (in. 1). 1 sp. Ceylon, yielding a pretty 
cabinet wood (nedun). 
Perilla Linn. Labiatae (vi. 11). 2 sp. E. Ind., China. 
