PERESKIOPSIS. 25 



1. PERESKIOPSIS Britton and Rose, Smiths. Misc. Coll. 50: 331. 1907. 



Trees and shrubs, in habit and foliage similar to Percskia; old trunk forming a solid woody 

 cylinder covered with bark and resembling the ordinary dicotyledonous stem; areoles circular, 

 spine-bearing or sometimes spineless, also bearing hairs, wool, and usually glochids; flowers similar 

 to those of Opmitia; ovary sessile (one species described as pedunculate), with leaves at the areoles 

 (except in one species); fruit red, juicy; seeds bony, few, covered with matted hairs. 



Type species: Opinitui brandegeei. Schumann. 



The plants are common in hedges and thickets of Mexico and Guatemala. 



As to the number of species to be recognized in this genus we are uncertain; about 16 

 have been described. In our first discussion of the genus (op. cit.) we recognized n 

 species, including several known only from descriptions. There now seem to be at least 

 10 species, of which 8 are in cultivation in Washington and New York. Two of the plants 

 were described, as early as 1828, as species of Pereskia, and here they remained with 2 

 later-described species until, in 1898, Dr. A. Weber transferred them to Opnntia, placing 

 them in a new subgenus, Pcrcskiopuntia. The same year Dr. Karl Schumann adopted 

 Weber's conclusions, publishing his treatment of the subgenus and assigning 5 species to it. 



In its large leaves and woody, spiny stems, this group suggests Percskia, but it has 

 glochids and different flowers, fruit, and seeds; in flowers, fruit, seeds, and glochids it re- 

 sembles OpiDitia, but on account of habit and foliage must be excluded from that genus. 



In view of these differences, Britton and Rose in 1907 established the genus Peres- 

 kiopsis and listed 1 1 species, 4 of which had been originally described as species of Percskia 

 and 5 as species of Opnntia. Since then we have grown most of these plants along with 

 the pereskias and opuntias so as to compare them. Unfortunately we are not able to 

 describe all the species fully, for they have never been known to flower in cultivation, 

 although some of the species, at least, bloom freely in the wild state. The leaves on the 

 lower parts of shoots are sometimes broader and shorter than those on the upper parts, 

 and in greenhouse cultivation the leaves of some species are narrower than when the plants 

 are growing under natural conditions. 



The generic name is from the Greek and signifies resembling Pereskia. 



KEY TO SPECIES. 



Stems, ovary, and often the leaves more or less pubescent. 



Normal leaves long-acuminate, narrow, with narrow cuneate bases i. P. vein! in a 



Normal leaves abruptly pointed, somewhat cuneate at base . . . 2. P. digitclii 



Stems, ovary, and leaves glabrous. 



Leaves, at least some of them, not much longer than broad. 



Fruit without leaves, at least so figured 3. P. opnntiaeflora 



Fruit with leaves subtending the areoles. 

 Areoles white, with few glochids or none. 



Leaves orbicular or nearly so, rounded or apiculatc 4. P. rotundifalia 



Leaves, at least the upper ones, obovate or elliptic, acute at both ends 5. P. cliaf>is!le 



Areoles dark, filled with numerous brown glochids 6. P. porteri 



Leaves, at least some of them, twice as long as broad or longer. 



Leaves spatulate 7. P. spathulata 



Leaves elliptic to oblong, or obovate. 



Leaves pale green, glaucous 8. P. pililaclie 



Leaves bright gr.en, shining. 



Glochids few, yellow 9. P. aqnosa 



Glochids many, brown 10. P. kcllcrntdiiii 



1. Pereskiopsis velutina Rose, Smiths. Misc. Coll. 50: 333. 1907. 



Stems weak and spreading, forming compact bushes 9 to 12 dm. high or sometimes higher; 

 old stems with cherry-brown bark; young branches green, borne nearly at right angles to the old 

 stem, velvety-pubescent; areoles bearing long white hairs and several short spines and some glochids; 

 leaves elliptic to ovate-elliptic, 2 to 6 cm. long by 1.5 to 2.5 cm. broad, acuminate, or acute at both 

 ends, dull green, more or less velvety-puberulent on both surfaces, when very young brighter green ; 

 flowers sessile on the second-year branches; ovary obovoid to oblong, pubescent, bearing large 



