Hydnocarpus
Gaertn.
Trees or rarely shrubs, evergreen, usually dioecious. Leaves alternate, entire or
serrate, coriaceous or subcoriaceous, pinnately veined; secondary veins upturned, gradually diminishing apically close to margin, connected to superadjacent secondaries by a
series of cross veins; petioles often thickened at apex; stipules foliaceous, caducous. Racemes axillary, few-flowered; flowers unisexual or bisexual, regular, 5- or rarely 4-merous. Male flowers in 1 - 4 bracteate racemose or cymose fascicles on short axillary peduncles. Sepals usually 4 - 5, free or slightly connate at base, imbricate, subequal, concave, caducous. Petals 4 - 5, or in multiples there of up to 16, free or connate at base, with a somewhat fleshy pilose scale at base inside. Stamens 5- many, free; filaments broadened towards base at least at anthesis; anthers oblong, reniform or sagittate,
basifixed; pollen tricolporate, reticulate, suboblate to subprolate. Ovary rudimentary, densely pilose, or absent. Female flowers solitary, or a few in fascicles on short axillary peduncles often arising from older nodes. Sepals and petals similar to but slightly bigger
than those in males. Staminodes 5 - many, sterile anthers mostly reduced in size. Carpels (3-) 4 - 5 (-6), connate into unilocular superior ovary; ovules 2 -
many in 6, 4 or 3 parietal
placentae; stigmas as many as placentae, sessile, radially spreading, recurved, deeply
bifid or bilobed and dilated at apex, glabrous above, pilose beneath. Fruit an indehiscent
berry large, globose or ovoid; pericarp thick and hard, or thin and fragile; exocarp
sometimes radially fibrous. Seeds angular-ovoid-oblong, usually with membranous aril,
trustaceous testa, oily endosperm and foliaceous cotyledons.
Rain forests of S. & S.E. Asia; ca 40 species, 4 in India.
Literature. SLEUMER, H. (1938) Monographie der Gattung Hydnocarpus Gaertner. Bot. Jahrb. 69: 1 - 94, tt. 1 - 4.
Notes. Taraktogenos Hassk. and Asteriastigma Beddome are treated as synomyms of Hydnocarpus Gaertn.
Among Indian species, the seeds of H. alpina, H. kurzii and H. pentandra produce oils commonly known as chaulmoogra oil, having high percentages of cyclopentenyl fatty acids. The true chaulmoogra oil is used extensively in the treatment of cutaneous diseases, especially leprosy. It has been replaced by the more preferred Hydnocarpus oil obtained from H. pentandra. However, at present sulphur drugs have replaced the usage of Hydrocarpus oil and its derivatives in the treatment of leprosy. Besides fatty acids, the seeds also contain cyanogenic glycosides discharging hydrocyanic acid and are used as fish poision.
The fruits set irregularly which remain on the tree and are harvested once in 2 - 3 years. They are suitable for planting as avenue trees in the hills and yield timber used or constructional purpose.
Rain forests of S. & S.E. Asia; ca 40 species, 4 in India.
Literature. SLEUMER, H. (1938) Monographie der Gattung Hydnocarpus Gaertner. Bot. Jahrb. 69: 1 - 94, tt. 1 - 4.
Notes. Taraktogenos Hassk. and Asteriastigma Beddome are treated as synomyms of Hydnocarpus Gaertn.
Among Indian species, the seeds of H. alpina, H. kurzii and H. pentandra produce oils commonly known as chaulmoogra oil, having high percentages of cyclopentenyl fatty acids. The true chaulmoogra oil is used extensively in the treatment of cutaneous diseases, especially leprosy. It has been replaced by the more preferred Hydnocarpus oil obtained from H. pentandra. However, at present sulphur drugs have replaced the usage of Hydrocarpus oil and its derivatives in the treatment of leprosy. Besides fatty acids, the seeds also contain cyanogenic glycosides discharging hydrocyanic acid and are used as fish poision.
The fruits set irregularly which remain on the tree and are harvested once in 2 - 3 years. They are suitable for planting as avenue trees in the hills and yield timber used or constructional purpose.
KEY TO THE SPECIES
| 1a. Sepals 4, petals 8 or more, stameens 15 - many | 2 |
| b. Sepals, petals and stamens 5 each | 3 |
| 2a. Leaves shiny; tertiary veins perpendicular, irregularly branched, perceptible on both surfaces; quaternary veins well developed, irregularly branched, forming a dense reticulum with tertiary veins and pinnately branched to end freely in the areole; petals 8 | 2. Hydnocarpus kurzii |
| b. Leaves not shiny; tertiary veins perpendicular, seldom branched, conspicuous only on the lower surface; quaternary veins scarcely develop reticulation and never end freely in the areole; petals 12 | 3. Hydnocarpus macrocarpa |
| 3a. Branchlets stellately puberulent; leaves entire, glabrous; tertiary veins somewhat irregularly arranged, together with quaternary veins form close reticulum; reticulum distinctly elevated and foveolate | 1. Hydnocarpus alpina |
| b. Branchlets simply puberulent; leaves serrate to remotely crenato-serrate, rarely subentire, minutely appressed pubescent at least along midrib and veins beneath; tertiary veins perpendicular, together with quaternary veins form sparse reticulum; reticulum neither elevated nor foveolate | 4. Hydnocarpus pentandra |
