ASCLEPIADACE^. (MILKWEED FAMILY.) 339 



commonhj valvate corolla, and in the singular connection of the anthers with 

 the stigma, the cohesion of the pollen into wax-like or granular masses (pol- 

 linia), etc., as explained under the typical genus Asclepias. 



PERfpLOCA GR!t:cA, L., a woody climbing plant of the Old World, in orna- 

 mental cultivation, and in one or two places inclined to be spontaneous, repre- 

 sents a tribe with granulose pollen loosely aggregated in two masses in each 

 anther-cell. It has a brownish rotate corolla, very hairy within, and with 5 

 awued scales in the throat. 



Tribe I. CYNANCHE^. Anthers tipped with an inflexed or sometimes erect scarious 

 membrane, the cells lower than the top of the stigma ; pollinia suspended. 



* Stems erect or merely decumbent. 



I Asclepiodora. Corolla rotate, merely spreading. Crown of 5 hooded fleshy bodies, 



with a salient (.'rest in each. Leaves alternate. 

 -. Asclepias. Corolla reflexed, deeply 5-parted. Crown as in n. 1, but with an incurved 



liorn rising from the cavity of each hood. Leaves usually opposite. 



3. Acerates. Corolla reflexed or merely sjireading. Crown as in n, 1, but with neither 



crest nor horn inside. Leaves mainly alternate. 



* ♦ Stems twining. Leaves mostly opposite. 



4. Enslenia. Corolla erect. Crown of 5 membranaceous flat bodies, terminated by a 2- 



cleft tail or awn. 



5. Vincetoxicum. Corolla rotate, spreading. Crown a fleshy 5 - 10-lobed ring or disk. 



Tribe II. GONOLiOBE.(E. Anthers with short if any scarious ti)), borne on the mar- 

 gin of or close under tlie disk of the stigma; pollinia horizontal. 



6 Gonolobus. Corolla rotate. Crown a wavy-lobed fleshy ring. Stems twining. 



1. ASCLEPIODORA, Gray. 



Nearly as in Asclepias , but the corolla-lobes ascending or spreading, and 

 the hoods destitute of a horn, widely spreading and somewhat incurved, slip- 

 per-shaped and laterally compressed, the cavity divided at the apex by a crest- 

 like partition. — Umbels solitary and terminal or corymbed, loosely -flowered. 

 Follicles oblong or ovate, often somewbat muricate with soft spinous projec- 

 tions. ('A cr/f ATjTrios and Sapov or Swpeo, tJie gift of ^Jsculapivs.) 



1 A. viridis, Gray. Almost glabrous; stems short (1" higb) ; leaves 

 alternate, short-petioled, ovate-oblong to lanceolate, 1-2' wide ; umbels sev- 

 eral in a cluster, short-peduncled ; floAvers large (1' in diameter), green, with 

 a purplish crown. (Acerates paniculata, Z)eca«s?«e.) — Prairies, 111. to Tex. 

 and S. Car. June. 



2. ASCLEPIAS, L. Milkweed. Silkweed. 



Calyx .5-parted, persistent; the divisions small, reflexed. Corolla deeply 

 .5-parted , the divisions valvate in the bud, reflexed, deciduous. Crown of 5 

 hooded bodies seated on the tube of stamens, each containing an incurved horn. 

 Stamens 5, inserted on the base of the corolla ; filaments united in a tube which 

 encloses the pistil ; anthers adherent to the stigma, each with 2 vertical cells, 

 tipped with a membranaceous appendage, each cell containing a flattened pear- 

 shaped and waxy pollen-mass ; the two contiguous pollen-masses of adjacent 

 anthers, forming pairs which hang by a slender prolongation of their sum- 

 mits from .5 cloven glands that grow on the angles of the stigma (extricated 

 from the cells by insects, and directing copious pollen-tubes into the point 



