696 MANUAL OF POISONOUS PLANTS 



weed (A. tuherosa) and {A. incarnata) and the {Vincetoxicum officinale) 

 contain the bitter glucoside asclepidin which is an amorphous, bitter, yellow 

 emetic substance. The root especially, which acts as an emetic, is recorded as 

 poisonous in Europe and cattle and other domestic animals will not eat it. 

 Friedberger and Frohner state that it causes diabetes and general weakness. 

 The caustic bush Sarcostemm-a aastrale of Australia is regarded in that coun- 

 try as poisonous. The Condurango (Marsdenia Cundurango), a South Amer- 

 ican vine, is used as an alterative. It is bitter and acrid. The root of 

 Asclepias stellifera of South Africa, according to J. Burtt Davy, yields an ex- 

 cellent rubber. 



Asclepias (Tourn.) L. Milkweed 



Perennial herbs with milky juice, entire leaves; flowers in umbels; calyx 

 S-parted, persistent, the lobes spreading; corolla deeply S-parted, reflexed dur- 

 ing flowering, deciduous; the crown consists of 5 hooded processes each con- 

 taining an incurved horn, enclosing the stamen tube; stamens 5, inserted at the 

 base of the corolla; anthers adherent to the stigma, each with 2 cells and con- 

 taining a pair of pear shaped masses of pollen (pollinia) ; ovaries 2; follicles 

 2; the stigma S-angled or 5-lobed; numerous seeds with a coma. About 85 

 species, mostly of the new world. Several members of the order are quite 

 weedy, especially in grain fields and pastures. 



Asclepias vestita Hook and Arn. 



Densely floccose-woolly, the white wool deciduous in age; leaves from 

 ■ovate to oblong-lanceolate very acute or acuminate, often subcordate, short 

 petioled or the upper sessile, 4-6 inches long; umbels 1-4, the terminal usually 

 peduncled, the lateral all sessile; corolla greenish-white or purplish, the lobes 

 ovate, 3 inches long, column very short; hoods nearly erect, ventricose, slightly 

 surpassing the anthers, entirely at the back of the somewhat truncate summit, 

 auriculate extended at the inner angle, the auricles or angles involute; the crest 

 not horn-shaped attached up to the summit of the hood, blunt not exserted; an 

 interior crown of 10 tooth-like processes in pairs between the hoods; ovaries 

 glabrous; follicles at first canescent. 



Distribution. California and adjacent regions. 



Poisonous properties. Said to be poisonous. The juice of this species and 

 of A. eriocarpa are irritating. 



Asclepias mexicana Cav. 



Stem 3-5 feet high; leaves in whorls of 3-6 or uppermost and lower op- 

 posite, sometimes also in axillary fascicles, linear or narrowly lanceolate (3-6 

 inches long, 2-6 lines broad) ; umbels corymbose, densely many flowered, on 

 peduncles longer than the pedicels; flowers greenish white, sometimes tinged 

 with purple; corrolla lobes oblong; hoods broadly ovate, entire, shorter than 

 the anthers, exceeded by the stout-subulate incurved horn. 



Distribution. In the southwest. 



Poisonous properties. Said to be poisonous. 



Asclepias speciosa Torr. Showy Milkweed 



A perennial from 1-4 feet high, white tomentose or canescent; leaves thick, 

 broadly ovate or oval, petioled; pedicel glabrate above; flowers greenish purple. 



