(18 ) 
4. Sanguisorba.—Perigonium calycine; limb 
4-cleft, colored. Stamens inserted on 
an annular throat (faux). 
5. Negundo.—Perigonium very small, 4- 
dentate. Fruit a 2-seeded samara, Tree. 
Shrub. 
II. Tetragynia. 
1. Tillwea.—Calyx 4-sepalous. Corolla 4- 
petalous. Follicles 4, each 2-seeded. 
2. Sagina.—Calyx 4-sepalous. Corolla 4- 
petalous. Capsule 4-valved. Seeds ren- 
iform. 
3. Cuscuta.—Corolla gamopetalous, 4-cleft. 
Ovary 1; ovules few, inserted on the. 
base of the ovary. Capsule circum- 
scissile. Parasitic. 
4. Potamogeton. —Perigonium 4-parted. 
Fruit; 4 sessile drupes. Aquatic. 
PENTANDRIA. 
I, Monogynia. 
A. Floral parts gamopetalous, inferior. 
a. Fruit 4 nutlets, each 1-2 seeded. 
aa. Ovary with 4 sutures finally sepa- 
rating into 4 nutlets. 
1. Heliotropium.—Corolla funnel-shaped, 
throat naked, limb plicate. 
