382 



ASCLEPIADACEvE. 



nally. Pollen-grains in each cell united into waxy pear-shaped 

 masses which are stalked and suspended in pairs from the summit of 

 the slits, each pair of stalks deriving its pollen-masses, not from the 

 cells of one anther, but from contiguous anther-cells of different 

 anthers. Pollination strictly entomophilous; the foot of the insect is 

 caught in the slit, and when drawn upward, drags out and bears 

 away the pollen-masses; in walking over other flowers, the insect's 

 foot is again drawn through a slit, and the pollen-masses are left 

 behind on the stigma, which is concealed beneath the cloven struc- 

 ture. Inflorescence cymose. Fruit consisting of 2 follicles. Seeds 



with a silky tuft of hairs at the micropyle. 



Stems terete, erect 1. Asclepias. 



Stems strongly flattened, prostrate 2. Solanoa. 



1. ASCLEPIAS L. Milkweed. 

 Perennial herbs with thick deep-seated roots. Stems strictly 



erect. Peduncles of the simple umbels generally placed between the 

 opposite leaves, but nearer one than the other. Bracts of the involu- 

 cre usually subulate. Calyx and corolla 5-parted, the divisions 

 reflexed, those of the former small, persistent, those of the Latter 

 deciduous. Stamens 5, inserted on the base of the corolla, the fila- 

 ments united into a tube which is blended above with the stylar 

 column and bears a circle of 5 hoods, each containing an incurved 

 horn, or hornless. Follicles ovate or lanceolate, one often abortive. 

 Seeds anatropous, flat, margined, imbricated on the large placenta. 

 Embryo large, with broad foliaceous cotyledons in thin albumen. 

 (Greek name of the European Swallow-wort, a plant of this family.) 



Hoods of the stamens with an incurved horn or crest projecting from or 

 contained within the cavity. 

 Herbage glabrous; leaves mostly in whorls of 3 to 6, linear or linear- 

 lanceolate; umbels on peduncles longer than the pedicels 



1. A. Mexicana. 



Herbage hoary-tomentose; leaves broad. 

 Umbels on peduncles longer than the pedicels. 

 Hoods twice as long as the stamen-column; corolla purplish; leaves 



opposite 2. A. speciosa. 



Hoods not exceeding the column; corolla creamy-white; some of the 



leaves in whorls of 3 or 4 3. A. t riocarpa. 



Lateral umbels sessile, the terminal one peduncled ; hoods not exceeding 



the column; leaves all opposite 4. A. restita. 



No horns to the hoods of the stamens. 

 Hoods conical, open down the front, a little exceeding the anthers; 



herbage glabrous, greenish or purplish 5. A. cordifolia. 



Hoods pointless, lower than the anthers, cleft half-way down the back: 

 herbage white-tomentose 6. A. Californica. 



1. A. Mexicana Cav. Stems slender, about 2 ft. high; herbage 

 glabrous; leaves in whorls of 3 to 6, or the lower and uppermost 

 opposite; leaves linear to linear-lanceolate, 1\ to 6 in. long, 2 to 6 

 lines broad, short-petioled; umbels many, often in whorls or corym- 

 bose, densely many-flowered, on peduncles longer than the pedicels; 

 flowers small, greenish white or tinged with purple; corolla-lobes 

 oblong, 2 lines long; horns slender, subulate, exported from the hood 



