Citrus maxima (Burm.) Osbeck, Reise Ostindien 250 (1765)

Synonyms
Aurantium x corniculatum Mill.
Aurantium decumana (L.) Mill.
Aurantium decumanum (L.) Mill.
Aurantium x distortum Mill.
Aurantium maximum Burm.
Aurantium x vulgare (Risso) M. G¨®mez
Citrus x aurantiifolia subsp. murgetana Garcia Lid¨®n et al.
Citrus x aurantium subsp. aurantiifolia (Christm.) Guillaumin
Citrus x aurantium var. crassa Risso
Citrus x aurantium var. daidai Makino
Citrus x aurantium var. decumana L. [Illegitimate]
Citrus aurantium var. decumana L.
Citrus x aurantium subsp. decumana (L.) Tanaka
Citrus x aurantium var. dulcis Hayne
Citrus x aurantium var. fetifera Risso
Citrus x aurantium var. grandis L.
Citrus x aurantium forma grandis (L.) M.Hiroe
Citrus aurantium var. grandis L.
Citrus x aurantium forma grandis (L.) Hiroe
Citrus x aurantium var. lusitanica Risso
Citrus aurantium var. sinensis L.
Citrus x aurantium var. vulgaris (Risso) Risso & Poit.
Citrus costata Raf.
Citrus decumana L. [Illegitimate]
Citrus grandis (L.) Osbeck
Citrus grandis var. sabon (Seibert ex Hayata) Karaya
Citrus grandis var. sabon (Siebold ex Hayata) Hayata
Citrus grandis var. yamabuki (Tanaka) Karaya
Citrus x humilis (Mill.) Poir.
Citrus hystrix subsp. acida Engl.
Citrus maxima (Burm.) Merr.
Citrus obovoidea Yu.Tanaka
Citrus pompelmos Risso
Citrus sabon Siebold
Citrus sabon Siebold ex Hayata
Citrus x sinensis var. brassiliensis Tanaka
Citrus x sinensis subsp. crassa (Risso) Rivera, et al.
Citrus x sinensis subsp. fetifera (Risso) Rivera, et al.
Citrus x sinensis subsp. lusitanica (Risso) Rivera, et al.
Citrus x sinensis var. sanguinea (Engl.) Engl.
Citrus x sinensis var. sekkan Hayata
Citrus x sinensis subsp. suntara (Engl.) Engl.
Citrus yamabuki Yu.Tanaka

Description
Tree, 5-10(-15) m tall, low-branching; branches spreading, spiny (seed propagation) or spineless (vegetative propagation), spines up to 5 cm long; young parts manifestly pubescent. Leaves ovate to elliptical, 5-10(-20) cm x 2-5(-12) cm, base rounded to subcordate, margin entire to shallowly crenate, apex obtusely acute, glandular dotted; petiole broadly winged, up to 7 cm wide, wing obcordate. Inflorescences axillary, with a cluster of a few flowers or a single flower; flowers large, 2-3 cm long in bud, 3-5 cm wide when fully expanded, pentamerous, puberulous; petals creamy-white; stamens 20-25(-35); ovary with 11-16 loculi. Fruit a subglobose to pyriform berry, 10-20(-30) cm in diameter, greenish-yellow, densely glandular dotted; peel 1-3(-4) cm thick; segments with large, pale yellow or pink pulp-vesicles, filled with sweetish juice. Seeds usually few, large, plump, ridged, yellowish, monoembryonic. [from PROSEA]

Ecology
The pummelo thrives in the lowland tropics. In the production centres of Thailand mean monthly temperatures are about 25-30 degrees C with a few cooler (and dry) months; the dry season lasts for 3-4(-5) months and annual rainfall is about 1500-1800 mm. The crop is not grown commercially above elevations of 400 m. Pummelo tolerates a wide range of soils from coarse sand to heavy clay. However, the tree prefers deep, medium-textured, fertile soils free from injurious salts. In this connection it is noteworthy that the best orchards in the 3 major pummelo provinces in Thailand are situated on the banks of current and former river courses.

Uses
The fresh juicy pulp vesicles are eaten out of the hand or in fruit salads; sometimes the juice is extracted. The white inner part of the peel can be candied after the outer peel containing oil glands has been removed. The aromatic flowers are used to make perfume in Vietnam. The wood is used for tool handles. Even if the fruit is of inferior quality, the tree may still be grown for the medicinal applications of leaves, flowers, fruits and seeds, including the treatment of coughs, fevers and gastric disorders.

Distribution
All over the (sub-)tropics. Originally from Asia, but the origin of the pummelo is uncertain. There is little doubt that the species is indigenous in Malesia. It has spread to Indo-China, southern China and the southernmost part of Japan and westwards to India, the Mediterranean and tropical America. However, it remains a fruit of the Orient; neither in India nor further west has it become popular. The best match of cultivars, environmental niches and growing skills appears to be found in Thailand.

Local names
Burma: shouk-ton-oh.
Cambodia: krooch thlong.
English: Pummelo, shaddock, pomelo.
French: Pamplemoussier.
Indonesia: jeruk besar, jeruk bali.
Laos: ki¨¨ngz s'aangz, ph'uk, somz 'oo. Malaysia: jambua, limau betawi, limau bali.
Papua New Guinea: muli.
Philippines: lukban, suha (Tagalog, Ilokano).
Thailand: som-o (general), ma-o (northern).
Vietnam: bu'o'i.