416 
NATURAL HISTORY OF PLANTS. 
to Picræna and Simaruba, but characterized by a thick disk, stamens 
covered with hairs, and albuminous seeds, while Picræna has a 3-5- 
lobed disk, stamens naked and glabrous, petals non-accrescent after 
anthesis, and exalbuminous seeds like those of Quassia. Picrolemma, 
Picrena excelsa. 
1 
1 

Fig, 472. 
Female floriferous branch (+). 
a small Brazilian shrub, with imparipinnate leaves, tetramerous, 
dicecious flowers, with four imbricated petals, the same number of 
superposed stamens, and a disk thick and elevated in the female 
tures alternately prominent within and without, 
five sepals, imbricated petals, two verticils of 
five stamens, with introrse slightly oscillating an- 
thers. At the bottom of the receptacle are two 
free carpels with obconical support, upon which 
is articulated a one-celled ovary with almost 
gynobasic style. On the internal wall of the 
ovary two collateral-descendent anatropous ovules 
are inserted with superior exterior micropyle 
capped by an obturator. Rigiostachys, whose 
fruit is unknown, is a Mexican tree (?) with 
alternate, stipulate, imparipinnate leaves, not 
bitter, and very numerous flowers united into a 
large ramified raceme, the tertiary divisions of 
which bear alternate bracts and pedicellate arti- 
culate fiowers, accompanied by two lateral 
bractlets. (See Adansonia, x. 42). 
