24 NATURAL HISTORY OF PLANTS. 
more flattened out than in the preceding genera, and is lined by a 
thick disk whose rim presents ten projections, alternating with 
which are as many notches corresponding with the stamens. These 
last are more external, and their filaments, exserted in anthesis, are 
twisted or corrugated in the bud. The gynzceum is borne on a 
slender stalk, and the style ends in a slight stigmatic dilatation. 
The pod is compressed and thick-walled, the endocarp projecting 
between the seeds to form more or less complete partitions. The 
pericarp finally opens down both edges. The seeds are attached to 
its interior by elongated funicles more or less bent on themselves. 
Stryphnodendron consists of trees or shrubs from tropical America. 
Their leaves are bipinnate, whose usually sessile leaflets, nearly as 
broad as long, have hairs scattered irregularly over their surface. Their 
flowers are also sometimes polygamous ; they grow in axillary racemes 
like those of Adenanthera. About half a dozen species are known.’ 
The flowers of Piptadenia® resemble those of Stryphnodendron,* 
and are sessile or shortly pedicellate.* They are hermaphrodite or 
polygamous, arranged either in more or less elongated racemes, or 
in spikes, which again may be also elongated, or else very short and 
sometimes globular (capitula). These inflorescences are pedunculate, 
axillary or terminal, either simple and solitary, or ramified. The 
pod, sessile or more frequently stipitate, opens like that of Stryphno- 
dendron, by two longitudinal clefts; but it has only a single cavity 
containing seeds suspended by slender funicles, for its membranous 
or coriaceous walls present no thickenings or false dissepiments 
between the seeds. In Piptadenia proper’ the pericarp is thin and 
smooth or reticulate. In Pytirocarpa’ the valves, thicker and more 
or less wrinkled on the surface, have their edges more or less pushed 
inwards in the intervals between the seeds. In both of these sub- 
genera the flowers are racemose. But Mopa, with the fruit of 
Pytirocarpa, has a capitular inflorescence ; while in a fourth small 
group, which we may term Piptoniopa, the fruit is that of Piptadenia 
1 AvBL., Guian., ii. 938, t. 357.—VxELLoz., rngated in the bud, but are afterwards long and 
Fl. Flum., xi. t. 7.—Parp. & Enpz., Nov. 
Gen. et Spec., iii. t. 291.—Watp., Rep., i. 860; 
v. 579. ‘ 
2 Bentu., in Hook. Journ., iv. 334,—B. H., 
Gen., 589, n. 376. 
3 These flowers are normally pentamerous, 
the receptacie is small and cupuliform with 
rounded fleshy edges ; the stamens are first cor- 
exserted in the flower, the ovary is stipitate, 
often hairy, and is surmounted by a truncate 
style; the ovules are descending, with the mi- 
cropyles looking upwards and outwards. 
« 4 The pedicels are articulated at either end. 
5 Eupiptadenia B. H., Gen., 590. 
6 B. H., Gen., loc. cit. 
