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swingle: a new genus of kumquat oranges 



FoRTUNELLA Swingle. Shrubs or small trees; young branches angu- 

 lar, the older ones rounded; spines borne singly at one side of the bud 

 in the axil of the leaf, or wanting. Leaves unifoliolate, rather thick, 

 blunt-pointed or even retuse, acute or rounded at the base; veins evi- 

 dent above, scarcely showing beneath; lower surface pale green, densely 

 glandular-dotted; petioles narrowly winged or merely margined, some- 

 times not articulated with the blade. Flowers borne singly or in few- 

 flowered clusters in the axils of the leaves, hermaphrodite, 5-merous 



(rarely 4-, 6-, or 7-merous) . Flower buds small, 

 8-10 mm. long, more or less angular in cross 

 section. Petals 5 (rarely 4 or 6), white, acute, 

 8-12 mm. long. Stamens 18 or 20, polyadel- 

 phous, cohering irregularly in bundles; filaments 

 broad but tapering at the tip. Pistil seated 

 on a well-marked disc; ovary subglobose, 3-7- 

 (usually 3-6-) celled, with two collateral ovules 

 in each cell; ovary merging gradually or abrupt- 

 ly into the short style, this usually shorter 

 than the ovary, sometimes shorter than the 

 stigma. Stigma capitate, symmetrical, cavern- 

 ous within because of the large deep-seated 

 oil-glands (fig. 1). Fruits small, 18-35 mm. 

 long, 18-25 mm. in diameter, oval or globose; 

 peel rather thick, fleshy and aromatic, sweet- 

 flavored, containing numerous large immersed 

 oil-glands. Segments 3-6, rarely 7 (figs. 2-5); 

 pulp vesicles small, fusiform or subglobose, 

 stalked, containing an acid juice. Seeds ovate in outline, smooth; 

 embryo pistache green. Germination with hypogeous cotyledons; first 

 foliage leaves broadly ovate, subsessile, opposite as in Citrus. 



Type species, Fortunella margarita {Citrus margarita Lour.), culti- 

 vated at Canton, China. 



Fig. 1. F. japonica. 

 Cross-section of stigma, 

 showing large oil glands 

 between stylar canals, 

 three of them double, 

 two single. Scale 25. 



The genus Fortunella resembles Citrus in the general appearance 

 of the stems, twigs, spines, leaves, flowers, and fruits and in having the 

 polyadelphous stamens normally four times as numerous as the petals. 

 It differs from Citrus (1) in having an isomerous or hypomcrous ovary, 

 normally 3-5-celled (rarely 6 or 7-), not polymerous (8-15- or more 

 celled), (2) in having two collateral ovules in each cell (not 4-12), 



(3) in having a cavernous stigma containing a few large, deeply im- 

 mersed, lysigenous oil glands (not asymmetrical and solid or nearly so), 



(4) in having the under surface of the leaves pale green, nearly veinless 

 and with very numerous, small, deep green glandular dots, (5) in hav- 

 ing a sweet and edible, more or less pulpy skin, and (6) in having small 

 more or less angular flower buds. 



