66 NATURAL HISTORY OF PLANTS. 
apex. Calyx toothed or lobed, more rarely polysepalous and short 
or nearly absent or composed of minute cilia. Petals free or 
oftener both connate and adnate to stamens to a variable height, 
valvate in estivation. Stamens o, usually very numerous; fila- 
ments slender exserted, hypogynous or oftener somewhat perigynous, 
inserted at summit of receptacle or under disk either free, or mona- 
delphous (Zophanta) or polyadelphous just at base or rarely to a 
greater height (A/dizzia), or monadelphous forming a long exserted 
tube (Zygia), always free at apex; anthers small introrse 2-celled 
2-rimose; pollen-grains usually aggregated in 2-4 masses in each 
cell. Germen sessile or stipitate, 2-c-ovulate; ovules 2-seriate 
descending ; micropyle extrorse superior; style slender; apex trun- 
cate or minutely capitate, stigmatiferous. Legume ovate, oblong 
or linear, plane convex or terete, straight or bowed, more rarely 
variously twisted, membranous coriaceous or ligneous, 2-valved or 
indehiscent, continuous, stuffed or septate within, more rarely sepa- 
rating transversely into l-seeded segments. Seeds transverse or 
descending, ovate or suborbicular, compressed ; funicle short straight 
or longer pendulous, more rarely very long corrugated or folded, 
variably dilated into a fleshy aril—Trees or shrubs, very rarely herbs, 
unarmed prickly or spiny; leaves alternate 2-pinnate; leaflets 
usually minute «-jugate, more rarely reduced to a compressed leaf- 
like petiole or phyllode; petiolar gland often more or less conspi- 
cuous; stipules 0, or of variable form, minute, more rarely broader 
membranous, sometimes spinescent straight or curved; flowers 
small, usually crowded, in globose heads or cylindrical dense or 
interrupted pedunculate spikes ; peduncles axillary, solitary or gemi- 
nate or more rarely fascicled or else in racemes at extremities of 
branches (Zropical Australia and Africa, all hot regions). See p. 37. 
21. Inga PLum.—Flowers 5-, more rarely 6-merous (of Acacia), 
hermaphrodite or more rarely polygamous; stamens connate at 
base to a variable height, forming a tube, usually at the same time 
adnate to base of corolla. Ovary sessile «-ovulate ; style subulate; 
apex truncate or capitate, stigmatiferous. Legume linear, straight 
or slightly curved, plane 4-gonous or terete, coriaceous or subcarnose, 
scarcely dehiscent ; sutures usually dilated thick furrowed. Seeds 
bare or enveloped in a sweet pulp.—Trees or shrubs, unarmed ; 
leaves abruptly pinnate ; leaflets often large ; petiole generally winged 
