CHARACTERISTICS OF THE ZONES OF MOISTUKE. 185 



Alhagi, Fagonia, Gum Acacias, and Acanthosicyos. 6. Shrubs with- 

 out prickles, but small, hard, rigid leaves, as Fabiana, Proteacese, 

 Larrea, Epacris, Bruuiacese. 7. Leaves, aud sometimes also branches, 

 gland-dotted, as Psoralea, Pvutaceae, Myrtaceae, or yielding gummy 

 exudations, like myrrh and frankincense. 8. Flowers protected 

 by an excessive development of scariose bracts, as Helichrysum, 

 (iomphrena, Barleria. 9. Dense hairiness or scarfiness on the leaf 

 bract and other foliar organs, as shown in Kochia, Eriocephalus, 

 Dalea and Aerua. 10. In the development of a tuberous root, 

 large out of all ordinary proportion in comparison with the stems and 

 leaves that come from it, as shown in Hoarea, Seymouria, Diposis, 

 Oxalis, and Brachystelma. 



In Monocotyledons we have the Xerophilous type represented in 

 two very characteristic forms, the large, thick, fleshy-leaved type, as 

 represented in Aloe, Gasteria, Hawerthia, 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- 

 cuses, Colchicums, Ixias, plants which usually inhabit not the heart 

 of the rainless tract but its border, where rain comes but seldom, and 

 which push up into leaf and flower in the brief season of fertility, 

 and spend the rest of the year in the form of an undergrouad mass of 

 dry or fleshy leaf scales, in the axils of some of which new plants 

 are formed by a process of vegetative reproduction which enables them 

 to hold their ground even if no seed be ripened. 



One of the most remarkable points about these Xerophilous 

 plants is the extraordinary way in which many familiar groups of 

 plants which are distributed through different climates are modified in 

 form in the Xerophilous belts. We have a very good instance of this 

 in Euphorbia, which is a genus of 700 species spread overall parts 

 of the world, all the members of which coincide 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 develop- 

 ment of scattered entire sessile simple leaves. About a hundred 

 species enter into the Xerophilous region, and these, whilst retaining 

 absolutely theii- floral structure, become so extremely modified in 

 habit that they are usually taken for Cactuses until the flowers are 

 looked at. I can only indicate roughly the general appearance of 

 two or three, taken at random. Euphorbia canariensis is a_ shrub 

 twenty feet high, with a general shape like a chandelier, throwing out 

 from the main stem copious firm, fleshy, ascending branches, a couple of 

 inches thick, without any leaves, each branch furrowed so as to have 

 five angles, and each angle armed with a row of pairs of pungent 

 prickles, which spread from the ridge at an angle of 45°. E. Tirucalli 

 is a tall bush, with copious slender, round, rodlike branches i to ^ inch 

 thick, without either leares, furrows, or prickles. The Cape E. poly- 

 gona has simple fleshy, cylindrical stems about a foot high, like those 

 of a Cereus in habit, grooved into a dozen deep furrows, each narrow 

 ridge armed with a row of close, large, simple, horizontal prickles. 

 The Cape E. meloformis is a top-shaped, leathery, tuberous mass, three 

 or four inches high and thick, without either leaves or prickles, with 

 eight ridges and eight grooves radiating from a central umbilicus and 

 curved down the sides. 



