CACTbSES IN- DOORS AND OUT. 



465 



Rhipsalis funalis. 



armed ,only with spines, as in mamillaria, echinocac- 

 tus and various euphorbias, or without spines, and 

 bearing fleshy or rigid leaves, as in cycads, welwitschia 

 and Vitis Baiiiesii and V. macropus: 3rd, branching, 



fleshy, or 

 hard stem 

 types, with- 

 out proper 

 leaves, but in 

 which the 

 main stems or 

 petioles put 

 on a leafy ap- 

 pearance, as 

 i n opuntia, 

 phyllocact u s 

 and the phyl- 

 lodineous ac- 

 cacias ;* 4th, 

 much branch- 

 ing shrubs, with copious whip-like branches without 

 either leaves or prickles, as rhipsalis, cassytha, and 

 Euphorbia Tiriicalli; 5th, much branched wiry herbs or 

 shrubs, with an excessive development of prickles, as 

 gum acacias ; 6th, shrubs with small, hard, rigid 

 leaves, as in the proteaceas and epacris ; 7th, leaves, 

 and often also branches, gland-dotted, as myrtaceae, 

 rutaceae and psoralea, or yielding gummy exudations, 

 like myrrh and frankincense ; 8th, flowers protected by 

 an excessive development of scariose bracts, as in heli- 

 chrysum and gomphrena ; gth, dense hairiness or scur- 

 finess on the leaf, bract, and other foliar organs ; 10th, 

 in the development of a tuberous root, large out of all 

 ordinary proportion in comparison with the stems and 

 leaves that come from it. 



"In monocotyledons (or parallel-veined plants) we 

 have the xerophilous type represented in two ver}' 

 characteristic forms ; the large, thick, fleshy-leaved 

 type, as illustrated by aloe, gasteria, haworthia, four- 

 croya, agave and bulbine ; and the familiar bulb type, 

 to which so many of our most beautiful open air garden 

 flowers belong — lilies, tulips, hyacinths, daffodils, cro- 

 cusses, colchicums, ixias — plants which mostly inhabit, 

 not the heart of the rainless tract, but its borders, where 

 rain comes but seldom and sparingly, and which push 

 up into the leaf and the flower in the brief season of 

 fertility, and spend the rest of the year in the form of 

 an underground mass of dry or fleshy leaf-scales, in 

 axils of some of which new plants are formed by a pro- 

 cess of vegetative reproduction which enables them to 

 hold their ground even if no seed be ripened. 



"One of the most remarkable points about these xero- 

 philous plants is the extraordinary way in which many 

 familiar groups of plants, which are distributed through 

 different climates, are modified in form in the xerophil- 



*Many of the acacias do not possess true leaves, but the petioles 

 or leaf-stalks are flattened and leaf-lil^e. These petiole-leaves are 

 called phyllodia. Most of our greenhouse acacias are phyllodin- 

 eous. — Ed. 



ous belts. We have an excellent instance of this in 

 euphorbia, which is a genus of 700 species, spread over 

 all parts of the world, all the members of which coin- 

 cide in the extremely peculiar structure of the flower. 

 About 600 of the species are annual or perennial herbs, 

 several of them widely-spread garden and cornfield 

 weeds, with slender unarmed stems, and a copious de- 

 velopment of scattered, entirely sessile, simple leaves. 

 About a hundred species inhabit the specially xerophil- 

 ous region, and these, whilst retaining absolutely their 

 floral structure, become so extremely modified in habit 

 that they are usually taken for cactuses by inexper- 

 ienced visitors to our living collections. 



" The large floras of decidedly xerophilous type are 

 five in number ; two in the northern and three in the 

 southern hemisphere, and are as follows : 



" ist. The desert flora, extending from the Canaries, 

 through the Sahara, and through Egypt and Arabia to 

 the Indus delta. This is not so rich in large groups and 

 large genera of decidedly xerophilous type as some of 

 the others, but it is the largest arid tract in the world, 

 and has a great many endemic genera and species. 



"and. The flora of southern California, New Mexico, 

 Texas and north Mexico, running out northward to 

 Utah and Kansas, but stopped in a southern direction 

 by the Mexican Andes. This is the exclusive home of 

 agave and its allies, fourcroya and beschorneria, and of 

 the rigid-leaved tree liliaceas, yucca, hesperalce, dasy- 

 lirion and beaucarnea, and it is the great center of the 

 cactuses. 



" Turning now to the southern hemisphere, we have : 

 "3rd. The flora of southern Angola, stretching down 

 the coast to the mouth of the Orange river, and across 

 the Kalihari desert and Cape Karroo to Kaffirland. 

 This is the great home of aloe (of which one large ar- 



Fig. N. Mamillaria (Anhalonium) fissurata. 



borescent species is said to reach 150 feet in the spread 

 of its branches), gasteria, haworthia, stapelia, mesem- 

 bryanthemum (of which latter genus alone there are 

 said to be not less than 400 species of extremely varied 

 habit), and of the cactus-like euphorbias. This is the 

 richest xerophilous flora in the world. 



