CITRUS 
3°7 
Cissus Linn. = Vitis Tourn. 
Cistaceae. Dicotyledons (Archichl. Parietales). 4 gen. with 160 sp. 
They grow in dry sunny places, especially on chalky or sandy soil. 
3 sp. in S. Am., the rest N. temp. (esp. Medit.). Shrubs and herbs 
with opp. leaves, often inrolled (cf. Ericaceae), with or without 
stipules. Glandular hairs are usually present. Firs, solitary or in 
cymose infl., $ , regular. K 5, the two outer ones usually smaller than 
the inner (they have sometimes been regarded as bracteoles, but these 
organs are found lower down) ; C 5 or 3 or o, convolute (the petals 
overlap to right or left according as the 3 inner sepals overlap to left 
or right respectively) ; A 00 on a sub-ovarial disc (sta. developed in 
descending order) ; G (5 — 10 or 3) i-loc. with parietal (often pro- 
jecting) placentae. Ovules 00 or 2 on each, ascending, orthotropous. 
Styles free. Capsule loculicidal. Endosperm; curved embryo. 
Genera: Cistus (ovules 00, capsule 5-valved), Helianthemum (do., 
3-valved), Hudsonia (ovules 2, pets. 5), Lechea (ovules 2, pets. 3 or o). 
Placed in Parietales by Benth. -Hooker, in Cistiflorae by Warming. 
Cistiflorae (Warming). The 10th cohort of Choripetalae (p. 137). 
Cistineae (Benth. -Hooker) = Cistaceae. 
Cistus (Tourn.) Linn. Cistaceae. 30 sp. Medit. C. creticus L. and 
C . ladaniferus L. yield the resin ladanum (not to be confused with 
laudanum), obtained by whipping the leaves with leather thongs. 
The drug was largely used in the plague and in nervous diseases, but 
is now little employed. Many sp. are favourite shrubs (gum-cistus). 
Citharexylum Mill. Verbenaceae (11). 20 sp. trop. Am. The com- 
mon name fiddle-wood is a corruption of Bois-fidele. 
Citriobatus A. Cunn. Pittosporaceae. 2 sp. S. W. Austr. 
Citrullus Forsk. Cucurbitaceae (in). 4 sp. Afr. , Medit., As. C. 
vulgaris Schrad. is the water-melon. C. Colocynthis Schrad. the 
colocynth, whose fruit furnishes the cathartic drug of the same name. 
Citrus Linn. Rutaceae (x). 30 sp. trop. Old World. .Shrubs and 
trees with usually simple leaves, which show a joint at the meeting 
place of blade and stalk, indicating their derivation from compound 
leaves like those of most of the order (cf. Berberis). Axillary thorns 
occur in some sp. ( = metamorphosed leaves of the branch shoot). 
Firs, in corymbs, $ . K and C 4 — 8. Sta. 00 in irregular bundles, 
corresponding to an outer whorl only. Cpls. 00 (6 or more), syncar- 
pous. A second whorl sometimes appears. Frt. a berry with leathery 
epicarp. The flesh is made up of large cells which grow out from 
the inner layer of the pericarp. 
Many sp. are cultivated in warm countries, for their fruit. C. 
Medica L., the citron, is the parent sp. of several varieties, e.g. var. 
Limonum the lemon, var. acida the lime, var. Lbnetta the sweet lime. 
C. Aurantium L. is the orange, with its varieties Bergamia , the 
Bergamot orange (from which the perfume is obtained), and Bigaradia 
the Seville or bitter orange. C . decumana Murr. is the shaddock. 
20 — 2 
