CACTUS 



CACTUS 



611 



722. Echinocactus flower, show- 

 ing insertion of stamens. 



723. Opuntia flower, 

 showing styles and 

 ovary. 



mass of stamens, as in the genus Echinocereus, in 

 which the emerald-green star contrasts prettily with 

 the golden-yellow or orange-colored stamens, rising 

 from a rosette of rose-purple petals (Fig. 724). The 

 ovary (Fig. 723), although formed of several carpels, 

 is 1-celled. The placenta? are parietal, bearing an in- 

 definite number of ovules, the stalks of which (funiculi) 

 become fleshy as the seeds develop and form a sugary 

 pulp around the seeds. 



The fruits of the Cactacese are variable in form. That 

 of the leafy Pereskia is apple-shaped and bears a num- 

 ber of leaf-like bracts on the skin (Fig. 725), on which 

 account the fruit of P. aculeata is 

 called blad-appel, or leaf-apple, in 

 the Dutch colonies, while in the 

 British West Indies it is known as 

 Barbados gooseberry and is made into 

 tarts and sauces like real goose- 

 berries. In some of the pereskiopses, 

 the fruit is elongated and shaped like 

 a prickly pear, with watery rind and 

 seeds covered with cottony hairs. In 

 Opuntia and Nopalea the fruit is 

 commonly called prickly pear, or 

 tuna (by the ancient Aztecs, nochtli) . 

 These fruits bear small fleshy leaves 

 at first, like the flattened pads of the 

 plants, and when the leaves fall off 

 the areoles persist armed with the 

 irritating sharp-barbed glochidia de- 

 scribed above (Figs. 717 and 726). Many species allied 

 to the genus Cereus bear edible fruits, usually called pita- 

 hayas. Those of the tall columnar cardones (Lemaireo- 

 cereus) are covered with easily detachable tufts of wool 

 and spines but never bear glochidia. Those of Cephalo- 

 cereus (Fig. 721) are spineless. The triangular climbing 

 forms which are often trained over garden walls in 

 tropical countries, sometimes bear enormous juicy 

 fruits of fine flavor (Fig. 727). Those of Echinocactus 

 (Fig. 728) are more or less scaly. The fruits of certain 

 species of Echinocereus, called alicoches by the Mexi- 

 cans, are known to Americans as strawberry cacti, on 

 account of the fine flavor of their juicy pulp. Those of 

 Echinocactus longihamatus are known in northern 

 Mexican markets as limas de viznaga, or cactus limes, 

 on account of their acid 

 taste; and the small 

 smooth crimson fruits of 

 many mamillarias are 

 called chilitos, on account 

 of their resemblance to 

 small chili peppers. Very 

 much like them are the 

 fruits of melon cacti (Fig. 

 729) which issue from the 

 dense crown of bristles like 

 scarlet radishes or fire- 

 crackers tipped with a fuse. 

 The seeds of the Cacta- 

 725. Pereskia fruit. cese vary considerably in 



724. Echinocereus flower, showing 

 radiate stigma. 



726. Opuntia fruit. 



the different groups, and are 

 sometimes useful in making 

 generic determinations. Thus the woolly seeds of 

 Pereskiopsis are sharply distinct from the black glossy 

 seeds of the genus Pereskia, with which the first-named 

 genus was at one time confused. In Opuntia and Nopa- 

 lea they are flat, hard and bony, somewhat ear-shaped 

 in the flat-jointed opuntias (Figs. 730, 733,) and usually 

 discoid and marginless in cylindrical opuntias (Figs. 730, 

 735) . In Cereus they are glossy black, with the testa 

 either quite smooth or minutely pitted (Figs. 730, 732); 

 in Echinocereus they are covered with minute tubercles 

 or granules (Figs. 730, 734). In Echinocactus, which is 

 not a very homogeneous group, the 

 seeds are pitted in some species and 

 tuberculate in others In one section 

 of Mamillaria (Eumamillaria) they 

 are glossy and marked with sunken 

 rounded pits (Figs. 730, 731), while in 

 another section, which should prob- 

 ably be made a distinct genus (Cory- 

 phantha) they are frequently smooth. 

 In the closely allied Ariocarpus they 

 are relatively large and tuberculate. 

 In the genus Pelecyphora, they are 

 sometimes kidney-shaped, as in P. 

 aselliformis, and sometimes of a pecu- 

 liar boat-like form with a very large 

 umbilicus, as in P. pectinata. In the 

 epiphytal Rhipsalis cassytha they are 

 kidney-shaped and finely granular. 

 The seeds of many of the species of Pachycereus ("car- 

 dones") are used by the Indians of Lower California and 

 Mexico for food. In south- 

 ern Puebla the fruit of 

 Pachycereus columna- 

 trajani, called tetezo figs 

 (higos de tetetzo) are a reg- 

 ular food staple, offered for 

 sale in the markets of 

 Tehuacan d u r i n-g the 

 month of May. 



Other cactus fruits of 

 great economic importance 

 are those of the giant 

 Cereus of our arid south- 

 western region, Carnegiea 

 gigantea, locally known as 

 pitahayas de sahuara, first 

 brought to notice in the 

 year 1540 by the members 

 of Coronado's expedition. 

 They are not spiny like 

 the fruits of Pachycereus 

 and they burst open when 

 quite ripe. The fruit of 

 Lemaireocereus Thurberi, 

 known as pitahaya dulce, 

 although much sweeter, 

 bears clusters of stout 

 spines issuing from tufts 727. Fruit of Hylocereus. 



