CATALOGUE. 131 



Bot. 50, t 19). — An erect, bushy plant, 10-12° high, with oval or sub- 

 cylindric joints, bearing on short oval tubercles 3-5 large (V long) and 

 many smaller spines, the larger ones loosely covered by glistening, whit- 

 ish sheaths ; purple flowers, small, 1 inch wide ; fleshy, greenish berry, 

 numerous small and very irregular seeds, or often abortive; wood a wide, 

 fragile tube with short meshes. 



Opuntia (Cylindropuntia) tessellata, Engelm. — Very bushy, from 

 a stout trunk, with solid wood, sometimes several inches thick; ultimate 

 branches as thick as a swan's quill, covered with angular, flattened, ashy- 

 gray tubercles, the uppermost bearing at their upper end single, long, loosely 

 yellow-sheathed spines; flowers small (about f of an inch wide), yellow; 

 small fruit, oval, covered with long, soft, brown bristles. Pac. R. Hep. I. c. 

 t. 2 1 . — On both sides of the Lower Colorado River, 6-7 ° high ; the yellow, 

 shining spines, crowded on the upper end of each year's growth, together 

 with the scale-like tubercles, give the plant a singular and striking appear- 

 ance. 



There are several other cylindric Opuntia in Arizona, not collected in 

 these Expeditions, and for the most part only imperfectly known. It is 

 desired to direct attention to this interesting group, which, on account of the 

 bulky forms and forbidding armament, are too much shunned by travellers. — 

 Opuntia echinocarpa, Engelm. & Bigel., is a low and very spiny bush, with 

 yellowish flowers and dry, spiny fruit. Opuntia acanthocatpa, Engelm. & 

 Bigel , is taller, with elongated tubercles, or rather ridges, copper-colored 

 flowers, and dry fruit bearing few, but stouter spines. 0. mamillata, 

 Schott, and fulgida, Engelm. & Bigel., are allied to 0. Bigelovii, with 

 thick tubercles or prominent crests, the former with small, the other 

 with numerous long and shining, sheathed spines; fruit often abortive. 

 Good specimens with flower, fruit, and good seed of the same plant 

 (so that mixing species and forms may be avoided) are very desirable, 

 as we know scarcely anything more about them than what the botanists 

 of the Mexican Boundary Commission (often at the most unfavorable season) 

 could find out, twenty-five years ago. Opuntia leptocaulis, DC. (O.frutes- 

 cens, Engelm.), the most slender Opuntia known, bushy, with branches like 

 pipe-stems, small yellow flowers, and red, somewhat fleshy berries, is common 



