118 



ASCLEPIADACEiE. 



ASCLEPIAS. 



Order LXXX. ASCLEPIADACEiE. R. Br. The Milkweed Tribe. 



Calyx 5-parted, persistent. Corolla regular, 5-lobed, deciduous, the aestivation 

 contorted ; the throat naked, or often furnished with five appendages which 

 adhere to the connate filaments, forming a crown (nectary, Linn.; lepanthium, 

 Nutt.). Stamens 5, inserted into the base of the corolla : filaments mostly 

 connate, and surrounding the pistil : anthers erect, introrse, 2-celled or in- 

 completely 4-celled : pollen, when the anther bursts, cohering into wax-like 

 masses, which are as numerous as the cells, or confluent by pairs, and finally 

 adhering through the intervention of the corpuscles and their arms to the five 

 angles of the stigma, by twos, by fours, or singly. Ovaries 2 : styles 2, ap- 

 proximated : stigma single, common to both styles, large and fleshy, 5-angled; 

 the angles alternating with the stamens, each of them bearing a small cloven 

 cartilaginous gland ( corpuscle ), with its two descending arms or processes. 

 Follicles 2, one of which is sometimes abortive. Seeds numerous, compressed, 

 imbricated, usually margined, with a long silky coma at the summit. Embryo 

 straight, with foliaceous cotyledons. Albumen thin. — Herbaceous or shrubby 

 lactescent plants, with mostly opposite entire leaves. Stipules none, but hairs 

 in their place between the leaves. Inflorescence umbellate, racemose or 

 corymbose ; the peduncles proceeding from between the leaves. 



For an account of the manner in which fecundation is effected in this singular order, see Mr. Brown's admirable 

 paper in the 16th volume of the Linnaian Transactions. 



1. ASCLEPIAS. Linn. ; Endl. gen. 3490 ; Decaisne in DC. prodr. 8. p. 564. 



SILK WEED. SWALLOW-WORT. 



[ The Greek name of Aesculapius, to whom the genus is dedicated.] 



Calyx deeply 5-parted ; the segments lanceolate, spreading. Corolla rotate, deeply 5-parted ; 

 the lobes lanceolate, refracted. Stamineal crown seated on the tube of the stamens, and 

 consisting of five cucullate lobes, each producing from its base a horn-like or subulate 

 averted process. Anthers with a membranaceous appendage at the summit. Pollen-masses 

 5 distinct pairs, pyriform, compressed, suspended by their attenuated summit in the cells of 

 the anthers. Stigma depressed. Follicles smooth, or muricate with soft spines. — Perennial 

 herbs, with opposite (rarely verticillate or alternate) leaves. Umbels between the petioles. 

 Roots thick and creeping, very tenacious of life. 



