A shrub or small tree, about 3 meters high, with a short, indistinct trunk and short, thick, irregular, straggling, thorny branches; bark light gray; thorns short, sharp, rather stout; young shoots smooth, violet colored or purplish, stiff; leaves large, 10 to 15 centimeters long, oval oblong, serrate or somewhat crenate, dark green above, lighter beneath; flowers small, axillary, in compact clusters of 3 to 10, often uninsexual; calyx small, cupped; corolla white within, tinged with purple on the outside; petals oblong, the tips incurved; stamens short, irregular in length, 40 to 45 in number; pistil small; [2] ovary 9 to 12 loculed or occasionally more; fruit lemon yellow, large, 15 to 22 centimeters long, oblong, rough or warty, sometimes ridged; apex blunt pointed; rind thick, white, except for the outer colored rim; pulp sparse; juice scant, acid, and somewhat bitter or sweetish; juice sacs small, slender; seeds oval, plump, light colored, smooth. Probably native to India, or it may have been introduced there from farther east, China or Cochin China. Extremely sensitive to cold. The citron is the rarest of all the old cultivated citrus in the Philippines and is very seldom seen in the markets. Citrus medica var. odorata. Tihi-tihi. (Pl. VIIa.) A small, thorny shrub, seldom exceeding 2.5 meters in height, with sharp, stout spines; young growth bright green; leaves 7.5 to 11 centimeters long, 4.3 to 6.5 centimeters broad, elliptical, rather thick and leathery, serrate, of distinct fragrance; base rounded; apex notched; petioles very short 4 to 6 millimeters long, not winged; flowers 1 to 4 in axillary compressed cymes, sessile, rarely exceeding 38 millimeters in diameter; calyx large, prominently cupped; petals 4 to 5, fleshy, white, with a tinge of purple on the outside; stamens 36 to 42, unequal, shorter than stigma; filaments united in groups of 4 to 6; pollen abundant; gynoecium frequently aborted; ovary elevated on a bright green disk, large, 4 millimeters long, 13 to 14 loculed; style tapering from ovary, scarcely more slender, rather short; stigma large, knob like, and cleft; fruit 60 to 65 millimeters long, 7 to 10 centimeters in transverse diameter, weighing 300 to 475 grams, oblate, with a shallow basal cavity, and sometimes a mammilate apex, more or less ridged longitudinally, fairly smooth, clear lemon yellow; lenticels scattered, depressed; oil cells large, equal or a trifle raised; skin rather thick; pulp grayish, rather dry, sharply acid, of lemon flavor; juice cells long and slender; seeds many--sometimes 125 in a single fruit--short, broad, and flattened. The tihi-tihi is a rare plant found in cultivation in Cebu and Bohol; one plant has been seen in Misamis, Mindanao. The plant is very precocious, fruiting as early as the third year from seed, everbearing, and is used by the Filipinos in washing the hair. It is not eaten, and is of no commercial importance.