1166 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Shrub, erect or nearly so, about a meter high ; leaves opposite, petiolate, 

 elliptic to ovate or oblong, 6 to 12 cm. long, abruptly acuminate, rounded at 

 base, puberulent or glabrate beneath ; flowers pale yellow, in lax axillary bifid 

 cymes ; calyx lobes lance-linear ; corolla salverform, glabrous, the tube 10 to 

 15 mm. long; follicles slender, torulose, 7 to 13 cm. long; seeds with an apical 

 tuft of long silky hairs. " Hierba de la cucaracha " (Durango, Sinaloa, Mi- 

 choac&n). 



The flowers are sweet-scented. The plant is used for poisoning cockroaches. 



141. ASCLEPIADACEAE, Milkweed Family. 



Plants ei'ect or scaudent, herbaceous or woody, with milky juice ; leaves 

 opposite, rarely verticillate or alternate, entire, estipulate ; flowers perfect, 

 regular, usually in cymes, these comntionly umbelliform or racemiform ; calyx 

 inferior, the tube very short or none ; corolla gamoi>etalous, rotate, campanu- 

 late, urceolate, or rarely funnelform or salverform, o-lobate; corona usually 

 present, adnate to the corolla or to the stamen tube, variously mod'fied; stamens 

 5, the filaments usually short and connate ; antliers basifixed, conniveut about 

 the stigma, forming with that and the filaments the gynostegium, 2-celled, 

 the cells usually produced below, the connective often with a membrane at 

 apex ; pollen usually coherent in masses known as pollinia ; 5 small corpuscles 

 present on the margin of the disk between the anthers, these attached to the 

 pollinia and supporting them after dehiscence of the anthers; ovary of 2 

 distinct carpels ; stigma usually forming a 5-angulate disk ; fruit of 2 follicles, 

 one of these usually abortive, sessile, dehiscent ; seeds often with a terminal 

 tuft of hairs. 



A large family, characterized by flowers of extremely complicated structure. 

 A few genera represented only by herbaceous species occur in Mexico. 



Pollen granular ; corolla funnelform, 5 to 7 cm. long, pink or purplish. 



Scandent shrub, glabrous or nearly so 1. CRYPTOSTEGIA. 



Pollen waxy ; corolla never funnelform, smaller. 



Pollinia borne in the lower part of the anther cell, pendulous from the 

 arms of the corpuscles. 



Plants erect 2. ASCLEPIAS. 



Plants scandent. 



Corona none 3. ASTEPHANUS. 



Corona present. 



Corona adnate to the corolla. 



Corona simple; corolla with a distinct tube 4. MACROSCEPIS. 



Corona double; corolla rotate. 



Outer corona thin, entire or nearly so 5. FUNASTRUM. 



Outer corona fleshy, 5-lobate 6. FISCHERIA. 



Corona adnate to the gynostegium. 

 Corolla lobes valvate in bud. 



Corona scales thin, flat 1 7. METASTELMA. 



Corona scales cucullate 8. BLEPHARODON. 



Corolla lobes contorted. 

 Leaves not cordate at base, usually linear to lanceolate, sometimes 

 ovate. 



Corona deeply lobate; stigma rostrate 9. BASISTELMA. 



Corona shallowly lobate; stigma conic 10. CYNANCHUM. 



