168 



RUTACEAE. 



CITRUS. 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. 



3. Leaves and fruit large. (Lemon). (2). C. Limonia. 

 Leaves and fruit small. (Fortunella) . (3). C. japonica. 



