698 ZIZANIA 



Zizaniopsis Doell. et Aschers. Gramineae (6). i Brazil, U.S. 



Zizia Koch (Caruni p.p. BH.}. Umbelliferae (ill. 5). 2 N.Am. 



Ziziphora L. Labiatae (vi). 12 Medit., C. As. 



Ziziphus Tourn. ex L. Rhamnaceae. 40 Indomal.. trop. Am., Afr., 

 Austr., Medit. Stips. often repres. by thorns; one is sometimes 

 recurved whilst the other is straight (cf. Paliurus) ; occasionally only 

 one is developed. Z. chloroxylon Oliv. (cogwood ; Jamaica) hard 

 tough wood. Fr. of many ed.; those of Z. Lotus Lam. (Medit.) 

 are said to be the Lotus fruits of antiquity; those of Z. vulgaris 

 Lam. (E. Medit.) are known as French jujubes; those of Z. Jozzeiro 

 Mart, are used in Brazil as fodder. Z. Spina-Chnsti Willd. is said 

 to have furnished the crown of thorns (cf. Paliurus). 



Zoegea L. Compositae (n). 5 W. As. 



Zoelleria Warb. Boraginaceae (iv). i New Guinea. 



Zoidiogamy, fertilisation by spermatozoids. 



Zoisia (Zoysia) Willd. Gramineae (3). 3 Masc. Is. to New Zealand. 



Zollernia Maximil. et Nees. Leguminosae (n. 9). 5 Brazil. 



Zollikoferia DC. = Launaea Cass. p.p. (Comp. ). 



Zollingeria Kurz. Sapindaceae (i). 2 Burma, Indochina. 



Zombiana Baill. Myoporaceae. i trop. Afr. 



Zomicarpa Schott. Araceae (vn). 3 S. Brazil. 



Zomicarpella N. E. Br. Araceae (vn). i Colombia. 



Zonantliemis Greene (Hemizonia p.p.). Compositae (5). 2 Calif. 



Zonanthus Griseb. Gentianaceae (i). i Cuba. 



Zones of vegetation, the six zones into which the earth can be 

 divided, occupied by similar types of vegetation with the same 

 periods of growth and the same general adaptation to environment. 

 The divisions are climatic-ecological, and the systematic relationships 

 of the plants are neglected (cf. Floral Regions). 



I. The northern Glacial Zone (the arctic region, and all beyond 

 the tree limit, whether towards the poles, or at high levels the alpine 

 zone). Period of growth usu. short, temperature low, soil liable to 

 be hot in the day, cold at night. Vegetation mainly xerophytic; 

 veg. repr. well marked. 



II. The northern Zone of cold winters (from the N. limit of trees 

 to the region where evergr. begin to predominate and the land is 

 parched in summer). Period of growth 4 7 months; summers not 

 usu. parching. Mesophytism predominant; vast areas covered by 

 forests; heaths and other formations of drier areas common. 



III. The northern Zone of hot summers (the subtrop. regions). No 

 real winter, but perhaps an interruption of vegetation in Jan. Xero- 

 phytism well marked, though some regions are wet. Forest, copse 

 (e.g. maqui, chaparral), steppe, and prairie all common. 



IV. The tropical Zone (wherever in the trop. the rainfall is enough 

 to prevent the formation of desert). No real interruption of vegeta- 

 tion. Forest (mesophytic) very common, also parkland or savannah. 



V. The southern Zone of hot summers; much like III. 



VI. The southern cold Zone: much like I. 



See Schimper, Plant Geography; Warming, Ecological PL Geog., &c. 

 Zoophily, pollination by animals. 

 Zornia J. F. Gmel. Leguminosae (in. 7). 12 trop., esp. Am. 



