60 KEY TO PLANTS. 
18 (a) Stamens 3-5. Seedsalbuminous. Shrubs 
or trees. Leaves translucently dotted. 
Flowers polygamous. Rutaceae. 
(0) Stamens 8. Seedsexalbuminous, Shrubs 
or trees. Leaves translucently dotted. 
Petals 4. Fruit drupaceous. Tropical 
America. Burseraceae. 
19 (2) Ovules attached to a basal or a free cen- 
@) _tral placenta. 20. 
(6) Ovules attached to a sutural placenta or 
to parietal placentas. 24. 
20 (z) Leaves opposite, entire, stipulate. Herbs 
or undershrubs. Petals 5, imbricate or 
open in bud. Stamens 3-5, as many as 
and alternate with the petals, or fewer. 
Fruit capsular. Caryophylleae. 
(2) Leaves alternate. 21, 
21 (2) Stamens fewer or more numerous than the 
petals.* Trees or shrubs. Leaves entire, 
exstipulate. Petals valvate. Ovules 3, 
suspended from the top of a central 
placenta. Fruit drupaceous. 
Olacineae. 
(6) Stamens as many as the petals, and op- 
posite to them. 22. 
* Compare Styraceae with 5 petals slightly coherent at 
the base, 10 stamens, and basal erect ovules. 
