POLYPETALOUS EXOGENOUS PLANTS. 279 



M. Texana. Heads l'-l|-' in diameter, l'-2|-' high, 

 usually covered below with young branches, and finally 

 densely ca^spitose; tubercles 3"-4" long, dark green ; axillm 

 quite woolly, with several coarse twisted bristles mixed 

 with the wool ; exterior hairlike spines covering the whole 

 plant as with a coarse wool, often 6"-8" long, whitish, with 

 dark tops, in robust ones yellow at base, brown upward, 

 and almost black at top; flotvers 7"-10" long. Along the 

 Rio Grande. — Dr. Posclger. 



M. sph.erica. Plants 2' long. If in diameter above, 

 narrowed below, the old tubercles withering and leaving a 

 short clavate scaly stem ; ovary exsert ; flowers quite large. 

 The tubercles soon become proliferous, and the branches 

 increase and reproduce often in such a manner as to form 

 large and hemispherical masses. Tubercles G"-8" long; 

 spines 3"-4" \o\\g\ floiuers lJ'-2' in length, and fully as 

 widely open in bright sunshine; tube slender, funnel-form, 

 remarkably constricted above the oval ovary. On Gulf 

 prairies. 



ECHINOCACTUS, Link and Otto. 



Sepals numerous, imbricated, adnate to the base of the 

 ovary and united in a very short tube, the exterior involu- 

 criform, the inner petaloid; stamens numerous; style Q\\- 

 form, many- cleft at the apex ; berry somewhat squamosa 

 with the vestiges of the s<d^\x\^.— Plant simple, ovate or 

 globose, leafless, with alternate vertical ribs and furrows, 

 the former bearing fascicles of spines ; spadix none ; flojuers 

 from the clusters of spines at the summit of the ribs, simi- 

 lar to those of Cerus, but with scarcely any tube. — De 

 Candolle. 



E. Texensis, Hoepf. Fi^iiit red and juicy, drying up 

 very soon; seeds 1-2 — 1-4 lines long, somewhat reniform, 

 with a deep indentation including the circular hilum ; testa 



