168 
CITRUS. 
RUTACEAE. 
Orange, Lemon. 
(Family Rutaceae). 
Aromatic shrubs or small trees, 
often with axillary spines: ever- 
green. Twigs moderate, green, 
more or less 3-sided: pith small, 3- 
sided, continuous. Buds solitary, 
sessile, small, round, with about 
3 scales, the end-bud deciduous. 
Leaf-scars alternate, crescent- 
shaped or half-round or _ lens- 
shaped, rather small, somewhat 
elevated: bundle-trace 1, round or 
elliptical: stipules and _ stipule- 
scars lacking. Leaves appearing 
simple but really of a single low- 
crenate pellucid-punctate leaflet 
disarticulating from the typically 
winged petiole. (Including For- 
tunella). 
Like the plum, olive and many 
other commonly cultivated fruit- 
trees and shrubs, the citrus spe- 
cies present a great variation in spininess. In addition to the 
citrange hybrids between the common orange and. Poncirus, 
crosses have been effected between the Tangerine type (C. no- 
bilis) and the grape fruit (C. grandis), which are called 
“tangelos”’; and between the lime (C. aurantifolia) and the 
kumquat (C. japonica). 
1. Leaves ovate, pubescent: petiole winged. C. grandis. 
Leaves lanceolate, glabrous. 2. 
2. Petiole moderately winged. (Orange). (1). C. Aurantium. 
Petiole narrowly winged. 
3. Leaves and fruit large. 
Leaves and fruit small. 
a 
(Lemon). (2). C. Limonia. 
(Fortunella). (3). C. japonica. 
