The panuban is said to bloom about New Year and the fruit ripens in September to November; the trees are reported to be very prolific. The panuban has been reported only from Lias, Bontoc, where half a dozen trees are said to grow. Possibly the panuban may be an accidental hybrid between the pomelo and the orange or mandarin; if it is simply a mutation it is certainly one of the most striking in this species. However this may be, the pomelo character is strongly dominant in both the foliage and the fruit. Very well flavored, the fruit is too dry to be acceptable to a discriminating public, but it is not improbable that under cultivation the juiciness would increase. In such a case the panuban might become a fruit of commercial importance.
A small, somewhat spiny tree, 4 to 6 meters tall; young growth greenish; leaves elliptic oblong, 4 to 9 centimeters long and about 4 centimeters wide, crenulate; base acute; apex usually emarginate; petiole scarcely winged, 10 to 15 millimeters long; flowers axillary, solitary, rarely in pairs, 21 millimeters in diameter, fragrant; petals white, reflexed; stamens 18 to 20, unequal; filaments united into groups; ovary globose, 6 to 8 loculed; style slender, distinct; stigma knoblike; fruit globose, orange yellow, 2 to 4 centimeters in diameter; skin smooth, thin, brittle, separable from the flesh; pulp orange colored, juicy, acid, with distinct aroma; juice cells rather large, short, and blunt; seeds comparatively large, smooth, plump, sometimes beaked; polyembryonic.
The calamondin is widely distributed in the Philippines and occurs wild as well as cultivated. The plant makes an attractive, ornamental, small tree and the fruit may be made into marmalade or utilized in making ade. There are no particularly distinct forms of this species. The trees are almost invariably very prolific and almost everbearing. In Bohol the species is known as "limoncito."
A shrubby tree with small, sharp spines; leaves averaging 95 millimeters in length, and 32 millimeters in width, oblong-ovate, crenulate, dark green and shining above; base broadly acute; apex emarginate, petiole 27 millimeters long; wings rarely exceeding 12 millimeters in width; flowers terminal, rarely axillary, solitary, 20 millimeters in diameter, sweet scented; calyx small; petals white, reflexed; stamens 19 to 21, about equal; filaments united into groups of several; ovary small, obovoid, 7 to 11 loculed; style distinct, slender; stigma small, club shaped; fruit sometimes attaining a weight of 165 grams, form oblate, 58 millimeters long to 65 millimeters long to 66 across, to roundish oblate, sometimes compressed and wrinkled toward base ending in a pronounced nipple; apex a shallow depression, or mammilate with the circular depression more or less pronounced; surface smooth to fairly smooth; color greenish yellow to lemon yellow, lenticels few, depressed; skin thin, the "kid-glove" character more or less pronounced; flesh whitish to grayish, very juicy, aromatic; juice cells variable, from short and blunt to medium slender and tapering to one end; seeds ovate, flattened, smooth, sometimes beaked.