10 NATURAL HISTORY OF PLANTS. 



of the st}de is very variable in form, sometimes linear, papillose on 

 one side or swollen and club-shaped, or with an irregular head, or 

 separated iuto papillose branches, as in Mirabilis, or even divided 

 into long- penicillate rays. The stamens are much exserted in the 

 greater part of the Pisonias proper, but in certain species, or in the 

 unisexual flowers, they protrude very little from the perianth, 1 and 

 the genus Neea? in everything else similar to the other Pisonias, is 

 distinguished only by its stamens, which should be constantly 

 included ; this, however, is not quite absolute. The greatest varia- 

 tions may be observed in the fruit and in the seed ; first as to the 

 indusium formed round the pericarp by the hardened portion of the 

 perianth. It is globular, ovoid, clavate, or much elongated into a 

 cone. The five prominent ribs which it bears are either naked and 

 little visible, or occupied by glands which cover it over with a 

 viscid secretion. These capitate and stipitate glands are prominent 

 at the surface (figs. 16, 17), and produce a very abundant glutinous 

 juice. The fruit fills all, or a variable portion, of this sac. The seed 

 which it encloses is occupied almost entirely by the embryo, which 

 is as long or longer than itself. In the latter case the cotyledons 

 are more or less corrugated in their length ; or their apex is 

 folded back more or less upon the base, 3 as in Mirabilis and other 

 analogous genera. Moreover, the two cotyledons envelop each 

 other. The more they enlarge the more concave they become on 

 the posterior side. Their curved edges bend to meet inside ; besides 

 which they are involute once or even several times upon themselves. 

 The albumen, becoming proportionally less as the cotyledons encroach 

 upon its mass, occupies the concavity, and is sometimes reduced to 

 a thin tongue, which fills the depression of each half of the posterior 

 cotyledon. Sometimes it is not more than a thin strip or a 

 sort of mucous filament/ occasionally even disappearing completely. 

 With all these variations in flower and fruit the Pisonias present 

 very constant characters in their organs of vegetation. They are 

 always trees or shrubs, inhabiting the warm regions of all parts of 



1 It is in the species of the New World that in Berl. AJcad. Abhandl. (1S31), 219; (1S32), 

 the stamens are described as included. t. 3. 



2 It. et PAT., Prodr., 52, t. 9; Fl. Per. et 3 This is seen in certain seeds of Vieil- 

 G'/iiL, 90. — J., in Ann. Mus., ii. 275. — Endl., lardia. 



Gen., n. 2011. — Cnois., Prodr., 447. — 4 For example, in Calpidiu lanceolata Dup- 



Nebra Nouonm., mss. — Mttsclierlichia K., Tu., and in several others. 



