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Pakistan | Family List | Rutaceae

Citrus Linn., Sp. Pl. 782. 1753. Gen. Pl. ed. 5341.1754; Hook. f., Fl. Brit. Ind. 1:514.1875; Tanaka, Sp. Problem in Citrus, Revisio Aurantiacearum, ix. 1-140.1954; Townsend in Davis, Fl. Turk. 2:507.1967; id. in Tutin et al., Fl. Eur. 2:229.1968.

Evergreen, small trees or shrubs, often spiny. Leaves simple, alternate, glandular punctate, petiole winged or margined. Flowers perfect or staminate, solitary or clustered in axillary racemes. Calyx 4-5-lobed, glabrous or pubescent. Petals (4-) 5(-8). Stamens 4-10 times the petals, polyadelphous. Ovary 10-14-locular, ovules biseriate or collateral. Fruit a fleshy hesperidium, globose to mamillate-oblong to oblate, rind tight or loose, with oil glands. Seeds embedded in pulpy vesicles.

Most or all of the species are cultivated, derived from the native species of tropical and subtropical regions of SE. Asia. Because of its great economic importance, domestication, cultivation and hybridization of the species has led to many varieties and forms, thus providing taxonomic problems. The following account of the species is primarily based on the work of Tanaka & Swingle with modifications in the treatment of the varieties.

Tanaka has described over 100 species. A genus widely cultivated. 10 species have been described from Pakistan.

1 Petiole broadly winged; wings more than 10 mm broad. Fruit more than 10 cm in diameter   (9)
+ Petiole wings less than 10 mm broad. Fruit 10 cm or less in diameter   (2)
2 (1) Leaf imperfectly articulated to the petiole. Petiole inconspicuously winged   Citrus medica var. acida
+ Leaf perfectly articulated to the petiole. Petiole narrowly winged   (3)
3 (2) Spines absent or short. Rind easily separable from the fruit. Axis not hollow in fruit   (4)
+ Spines always present. Rind not easily separable from the pulp vesicles. Axis hollow in fruit   (5)
4 (3) Fruit 5-8 cm in diameter, rind usually rough and warty. Stamens more or less united into a tube. Flowers 1-few   Citrus reticulata
+ Fruit c. 3 cm in diameter; rind smooth. Stamens not united into a tube. Flowers solitary   Citrus madurensis
5 (3) Fruit ovoid or rounded, usually mamillate   (6)
+ Fruit rounded or subglobose, never mamillate   (7)
6 (5) Leaves small and narrow (3.5-6 x 1.5-2.8 cm), crenate. Ripe fruit greenish-yellow   Citrus aurantifolia
+ Leaves elliptic to ovate (6.5-10 cm), serulate. Ripe fruit yellow   Citrus limon
7 (5) Flowers perfect and staminate. Stamens c. 35. Rind green or pale-yellow in ripe fruit   Citrus limetta
+ Flowers perfect. Stamens 20-25. Rind orange in ripe fruit   (8)
8 (7) Wings of petiole oblanceolate. Fruit with pulp sweet or subacidic when ripe   Citrus sinensis
+ Wings of petiole obovate. Fruit pulp sharply acid   Citrus aurantium
9 (1) Midrib and veins pubescent. Pulp vesicles loosely packed. Seeds ridged   Citrus grandis
+ Midrib and veins glabrous. Pulp vesicles closely packed. Seeds smooth   Citrus paradisii

Lower Taxa

Related Synonym(s):


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