538 CACTACEAE 



or, in Opuntia. bearinj? small subulate early-deciduous leaves. Flowers usually 

 perfect, solitary or clustered, sessile. Sepals and petals numerous, intergrading, 

 imbricated in several rows, their bases usually coalescent, forming a tube or cup 

 superior to the ovary. Stamens numerous; filaments inserted on the throat of the 

 perianth; anthers 2-celled. Style 1; stigma-lobes 1 to numerous; ovary 1-celled; 

 ovules numerous, parietal. Fruit a berrj', juicy, fleshy or drj'; seeds usually nu- 

 merous, smooth, granulate, punctate or tuberculate; testa coriaceous or bony; 

 endosperm copious or scanty; radicle terete. — Genera 26, species about 1173, char- 

 acteristic of the more arid regions of North and South America. 



Bibliog. — Engelmann, Geo., papers on Cactaceae in his Botanical Works, 109-236 (1887). 

 Coulter, J. M., Preliminary revision of N. Am. species of Cactus, Anhalonium and Lophophora 

 (Contrib. U. S. Nat. Herb. 3:91-132, — 1894) ; Preliminary revision of N. Am. species of Echino- 

 cactus, Cereus and Opuntia (I.e. 3:357-462, — 1896). Brandegee, K., Notes on Cactaceae (Ery- 

 thea 5:111-123,-1897). Schumann, K., Gesamtbeschreihung der Kakteen, 1-832, figs. 1-117 

 (1898). Britton, N. L., & Eose, J. N., The Cactaceae, l:i-vii, 1-236, figs. 1-302, pis. 1-36 

 (1919) ; 2 :i-vii, 1-239, figs. 1-304, pis. 1-40 (1920) ; 3 :i-vii, 1-255, figs. 1-250, pis. 1-24 (1922) ; 

 4:i-vii, 1-318, figs. 1-263, pis. 1-36 (1923). Vaupel, F., Cactaceae (Engler, Nat. Pflzfam. 21: 

 594-651, figs. 271-288,-1925). Parish, S. B., Notes on Cactaceae (Bull. S. Cal. Acad. 25 :83-84, 

 — 1926); Cactaceae in Jepson, Man. 654-660 (1925). Berger, A., Die Entwicklungslinien der 

 Kakteen, 1-108, figs. 1-71 (1926). 



Stems jointed, either cylindrical or flattened ; areoles containing numerous minute barbed bristles 

 (glochids) ; leaves small, subulate, early caducous; flowers and barbed spines produced 

 from the same areoles 1. Opuntia. 



Stems continuous, leafless; areoles destitute of glochids; spiniferous and floriferous areoles dis- 

 tinct ; spines not barbed. 

 Stems globose, ovoid, cylindrical or columnar, ribbed ; spines borne in clusters on the ribs. 

 Flowers produced above mature spine-clusters, below the summit of the ribs-2. Cereus. 

 Flowers produced above nascent spine-clusters, at or near the summit of the ribs 



3. ECHINOCACTUS. 



Stems globose or cylindrical ; spines borne on mammilliform tubercles, and the flowers pro- 

 duced between the spiniferous tubercles. 

 Flowers produced in the axils of mature spiniferous tubercles, and below the summit of 



the stem 4. Mammillaria. 



Flowers produced in the axila of nascent spiniferous tubercles, at or near the summit of 

 the stem 5. Coryphantha. 



1. OPUNTIA Mill. 



Plants shrub-like or arborescent, with jointed, cylindrical and tuberculate or 

 flattened stems. Areoles produced at the axils of the small, early-caducous leaves, 

 and bearing numerous glochids, and usually spines and wool. Flowers with rotate 

 corollas; sepals thick, green or partly colored, grading into the yellow, purplish 

 or reddish petals; stamens numerous, shorter than the petals; stigma-lobes short; 

 ovarj' bearing leaves and glochids, and either spiny or spineless. Fruit succulent 

 or drv', obovate or globose, truncate; seeds large, meniscoidal or discoidal, often 

 margined; cotyledons foliaceous; embryo curved. — Species about 250, North and 

 South America. (Ancient Latin name, formerly belonging to some other plant.) 



The cylindrical-stemmed species are called Chollas (Choyas), and the flat-stemmed ones 

 Tunas, a name also applied to their fruits. Species which produce palatable fruits are exten- 

 sively cultivated in Mexico, and to a less extent elsewhere; they are also utilized for hedges. 

 Some which have few or no spines are cultivated for forage ; in times of scarcity the spiny wild 

 species are gathered and fed to cattle, the spines being first singed off in the blaze of fires. 

 Starving cattle will even eat the untreated plants, and on the deserts they are gnawad by rodents. 



Bibliog. — Griffiths, D., Illustrated studies in the genus Opuntia (Rep. Mo. Bot. Gard. 19: 

 259-272,-1908; 20:81-95, pis. 2-13,-1909; 21:165-174, pis. 19-28,-1910; 22:25-36, pis. 

 1-18,-1911) ; New species of Opuntia (Proc. Biol. Soc. Wash. 27:23-28,-1914; I.e. 29:9-15,— 

 1916; Bull. Torr. Club 43:83-92,-1916). Britton, N. L., and Eose, J. N., A preliminary treat- 

 ment of the Opuntioideae of N. Am. (Smithson. Misc. Coll. 50:503-539, — 1908). 



A. Joints cylindrical, tuierculate. — Subgenus Cylindropuntia. 

 Spines polished, covered with loose hyaline sheaths. 



Stems slender, the woody axis solid; tubercles flattened 1. 0. ramosissima. 



Stems thick and fleshy, the woody axis a reticulate cylinder. 



