Polemonium .] lviii. convolvulace^e. 
235 
quite a different habit from the true Menyanthes. Stigma 5-cleft. Mr. 
Brown first observed that, in all the aquatic species of this genus, the 
capsule is valveless; 2-valved in the others; hence Grisebach has 
divided it ipto two genera, Limnanthemum and Villarsia : our British 
species belongs to the former. 
Ord. LVII. POLEMONIACEiE Jvss. 
Calyx of 5 divisions, persistent, sometimes irregular. Corolla 
regular, 5-lobed. Stamens 5, from the tube of the corolla. 
Ovary single, 3-celled; ovules solitary in each cell or super- 
posed. Style simple. Stigmas 3. Capsule 3-celled, 3-valved, 
valves separating from the axis. Embryo straight. Albumen 
horny. — Herbaceous plants. Leaves simple or compound, oppo- 
site or alternate. 
1. Polemonium Linn. Jacob’s Ladder. 
Cor. rotate. Stam. inserted upon the 5 teeth or valves which 
close the mouth of the corolla. Capsule inany-seeded. — Named 
from 7ro\fjuo£, war, according to Pliny; this plant having caused 
a war between two kings who laid claim to its discovery 1 
1. P. caruleum L. ( blue J.) ; leaves pinnate glabrous, 
leaflets oblong-lanceolate. E. B. t. 14. 
Banks and bushy places, rare ; chiefly found in the north. In 
Derbyshire and Yorkshire. About Queensferry, Arniston, Bonnington 
and Delvine woods, Scotland, but probably introduced. Knockmaron 
Hill, Ireland. 'll. 6,7. — Stem 1 — 2 ft. high, angular. Flowers 
large, blue, sometimes white. 
Ord. LVIII. CONVOLVULACEiE Juss. 
Calyx of 4—5 sepals, permanent, imbricated, often very un- 
equal. Corolla regular, deciduous ; the limb plaited, 4-5- 
lobed. Stamens 4 — 5 from the base of the corolla. Ovary with 
2 — 4 cells, seldom 1, sometimes in 2 or 4 divisions, few-ovuled, 
ovules solitary in each cell or collateral. Style 1, often divided, 
rarely 2. Disk annular, hypogynous or wanting. Capsule 1 — 4- 
celled, the valves fitting at their edges to the angles of a loose 
dissepiment, bearing the seeds at the base, or bursting trans- 
versely. Albumen in small quantity, mucilaginous. Embryo 
curved. Cotyledons plaited. — Herbs or Shrubs, generally 
climbing, milky, and purgative . Leaves alternate or wanting. — 
Scarnmony is the product of Convolvulus Scammonia ; jalap, of 
Exogonium purgans. The sweet potato , a most valuable escu- 
lent root of the tropics and warm climates, is the Batatas 
esculenla. Cuscuta has no leaves, and is parasitical. 
1. Convolvulus. Calyx not inclosed within bracteas. Capsule 2- 
celled, 2-valved. Stems leafy. 
2. Calystegia. Calyx enclosed within 2 bracteas. Capsule 1-celled, 
2-valved. Stems leafy. 
