542 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1908. 



The ovary, though formed of several carpels, is always one celled. 

 The placentae are parietal and bear an indefinite number of anatro- 

 pous ovules. In some genera (Opuntia and its allies) the funiculi, 

 or ovule stalks, become thick and fleshy as the seeds develop, and 

 finally form a more or less sugary pulp in which the seeds are 

 imbedded. 



FRUIT. 



Pereskia has a fruit somewhat like an apple in shape with a number 

 of leafy bracts on the skin," so that in the Dutch West Indies the 

 fruit of P. aculeata is called " blad-appel," or '' leaf apple." In the 

 British islands it is Imown as the Barbados gooseberry, and is used 

 for making tarts and sauces, very much after the manner of true 

 gooseberries. In some of the Pereskiopses the fruit is elongated and 

 opuntia-like with a watery rind, as in the tunas de agua of Guada- 

 lajara, and with seeds covered wdth cottony hairs. In Opuntia and 

 Nopalea the fruit is a tuna (in the ancient Nahuatl, called 

 " nochtli ") . Tunas are set with areoles like the stems or joints of the 

 plant itself, and when immature bear leaves (pi. 10, fig. 6). Tliese 

 eventually fall off leaving little tufts of barbed bristles or glochidia 

 in their axils (pi. 9, fig. 6). Many species of the genus Cereus 

 and its allies bear edible fruit. Those of the tall columnar cardones, 

 called pitahayas,^ are often covered with tufts of wool and spines, 

 which are detached easily when the fruit is ripe, leaving it covered 

 with scars (pi. 9, fig. 5). The triangular forms of Cereus usually 

 bear edible pitahayas also (see pi. 12), some of them of enor- 

 mous size and delicious flavor, and in Texas and northern Mexico 

 several long-spined alicoches (Echinocereus spp.) are known to 

 Americans as " strawberry cacti," from the delightful flavor of their 

 succulent berries (pi. 9, fig. 3). I have already referred to the acid 

 limas de viznaga, as the fruit of Echinocactus longihamatus is called 

 in Nuevo Leon (pi. 9, fig. 4), as well as to the smooth red chilitos 

 borne by various Mamillarias (pi. 9, fig. 1) and the currant-like 

 garambullas of the arboreous MyrtiUocactus geometrizans (pi. 9, fig. 

 2). Very much like the fruit of a Mamillaria is that of the genus 

 Melocactus, in some species of which the little chilitos issue from the 

 crown like scarlet radishes or crimson firecrackers tipped with a 

 fuse (pi. 1, fig. 2). 



The seeds of Cactacese vary considerably in the different groups 

 and are sometimes useful in making generic determinations. In Per- 

 eskia they are comparatively small with a thin black glossy testa, or 



« See Rose, J. N. Contr. Nat. Herb., vol. 12, p. 399, pi. 54. 1909. 

 ^ In Central and South America the name tuna is sometimes applied to fruits 

 of Cereus. 



