Opiliaceae

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Opiliaceae

Description

Most species are small trees of about 3-8 m, sometimes gregariously growing (Urobotrya spp.) or tiny shrubs (Lepionurus often less than 1 m high); only Champereia and Melientha can attain sizes of more than 10 m. The lianas (Cansjera and Opilia) are climbing up to 30 m, but they are often recorded as erect shrubs, too. The stem of a young Cansjera rheedii is growing in an inclined position and the branches are spreading (cf. ); if there is no tree for climbing up it becomes an erect shrub. Small evergreen trees, shrubs or lianas; Leaves distichous, simple, usually extremely variable in form and size, entire, exstipulate, pinnately veined; Cystoliths occur in all representatives, commonly in pairs of clusters in enlarged mesophyll cells or ray cells of the vascular tissue. Size, shape and refractive properties seem to be taxonomically relevant. Within the family, uniseriate and branched hairs (the last mentioned in species of Opilia, Rhopalopilia and Cansjera) are found. They may cover leaf surfaces, or may be restricted to midrib and veins, or are lacking. Stomata are paracytic with two to several subsidiary cells. Some variation in differentiation of the mesophyll is found: either a homogeneous tissue of cubic cells, or two layers of palisade parenchyma and spongy parenchyma, with or without a hypodermis.

Both wood and leaf characters point to a very close relationship between Champereia and Melientha. Of the other Malesian taxa, Gjellerupia, Lepionurus, and Urobotrya are very similar. Opilia and Cansjera, as well as the African Rhopalopilia and the neotropical Agonandra, seem to have a slightly isolated position.
— J. KOEK-NOORMAN.
Inflorescences axillary or cauliflorous, panicle-like, racemose, umbellate (in Africa) or spicate; Flowers small, (3-) 4-5) (-6)-merous, mainly bisexual, sometimes unisexual and plants then dioecious (Gjellerupia, Melientha, and Agonandra) or gynodioecious (Champereia). Stamens as many as and opposite to the tepals (in ♀ flowers only small staminodes); Ovary superior, 1-celled; Ovule 1, pendulous from the apex of a central placenta, anatropous, unitegmic and tenuinucellar. Fruit drupaceous, pericarp rather thin, mesocarp ± fleshy-juicy, endocarp woody or crustaceous. Seed large, conform to the drupe, without testa;

Distribution

Africa: present Asia-Tropical:, New Guineapresent Madagascar: present South and Central America: present Tropical Africa: present eastern Old World: present
There are 9 genera with about 30 spp., widespread in the tropics. Rhopalopilia is restricted to Africa and Madagascar, Agonandra to South and Central America. In Malesia: 7 genera, 5 of these only known from the eastern Old World (1 endemic: Gjellerupia in New Guinea); Opilia and Urobotrya occur also in tropical Africa.

Ecology


Pollination

The flowers of all species of this family possess nectar-secreting disks; some flowers are fragrant. They are evidently entomophilous. The inflorescences of Champereia manillana are often visited by ants.

Dispersal

The fruits of Opiliaceae are drupaceous and vary in size from less than 1 cm long (Champereia) to 4 cm (Melientha). For Champereia it is reported that the fruits are eaten by birds.

Morphology

The panicle-like inflorescences of Champereia and Melientha are irregularly branched (, ), the flowers are pedicelled or sessile. In the racemose inflorescences of some genera the pedicelled flowers are arranged in ternate groups (in the axil of each bract) along the rachis, showing that these inflorescences are not genuine racemes but more complex types of inflorescences. Occurrence of bracteoles in some species of Urobotrya stresses this opinion.

The perianth of Opiliaceae was often described as composed of a 'minute and inconspicuous' calyx and ± free petals. Other authors use these terms only for the description of Opilia, whereas the flowers of the other genera are called monochlamydeous (e.g. ). Since the flowers of Opilia show solely a slightly cupuliform torus which hardly can be called calyx, I use the terms perianth and tepals for the entire family.

Taxonomy

Before VALETON (1886) established the Opiliaceae as a distinct family the genera of this group have been placed by different authors in several other families. BENTHAM& HOOKER (1862) e.g. treated the tribe Opilieae (Lepionurus, Cansjera, Opilia, and Agonandra) as a part of their Olacineae, whereas Champereia was a member of their Santalaceae (B. & H., 1883). In the treatment of BAILLON (1892) the Opilieae (including Opilia, Lepionurus, Champereia, Melientha, Agonandra, and Cansjera) made part of the family Loranthaceae, which included also the Olaceae, Santaleae and several other groups today mostly considered to form distinct families. ENGLER (1889) treated Champereia also as a genus of Santalaceae; the other genera of our Opiliaceae were placed in two different tribes of the family Olacaceae, namely the Opilieae (Opilia, Cansjera, and Lepionurus) and Agonandreae (Agonandra).

In 1897 ENGLER accepted the family Opiliaceae as established by VALETON (l.c.) and transfered Champereia according to the treatment of VALETON from Santalaceae to the tribe Opilieae of this family. In the classification of SLEUMER (1935) the same two tribes are set down: Opilieae and Agonandreae. The second tribe is composed of the genera Gjellerupia and Agonandra. Since Gjel-lerupia is, with respect to morphological, anatomical, and palynological characters, obviously more closely allied to Urobotrya and Lepionurus it has also to be included in the Opilieae.

Most present-day authors consider Opiliaceae in our circumscription as a distinct family placed along with Olacaceae and Santalaceae in the order Santalales (or Olacales). THORNE (1981) very recently included this family in the rank of a subfamily in his Olacaceae.

Cytology

Chromosome numbers of 3 spp. have been recorded, two of these species occur in Malesia: Lepionurus sylvestris (n = 10) and Opilia amentacea (= O. celtidifolia, 2n = 20, African material counted). The neotropical Agonandra racemosa has the same chromosome number (n = 10).

Uses

Young leaves and inflorescences (incl. young fruits) of Champereia manillana and Melientha suavis are frequently used as a vegetable. The fruits (juicy mesocarp) of some species are also eaten locally and occasionally: Cansjera leptostachya (Northern Australia), Champereia manillana (in many parts of the range), Melientha suavis (in Thailand), and Opilia spp. (in Northern Australia and different parts of Africa).

Some species are used in local folk medicine (pounded or as a decoction): Champereia manillana (leaves and roots applied for ulcers, rheumatism, headache, and stomachache); Lepionurus sylvestris (roots or whole plant applied for fever or headache); Opilia amentacea (roots and/or leaves are in Africa applied for fever, headache, or intestinal parasites; in W. Africa the plant is said to have a purgative, diuretic, and abortive action); Urobotrya siamensis (in Thailand used for a medicine against intestinal parasites, in large amount a deadly poison).

The wood of Melientha suavis is often used for charcoal in Thailand.

Phytochemo

HEGNAUER (1969) stressed the paucity of phytochemical information on Opiliaceae. The most interesting feature then known was the presence of acetylenic fatty acids in the lipids of roots, stem and leaves of Cansjera leptostachya BTH. This connects Opiliaceae biochemically with Olacaceae and Santalaceae. In the meantime phytochemical screenings of some medicinally used African Opiliaceous plants demonstrated the presence of saponins in two Mada-gascan species of Rhopalopilia (DEBRAY C.S., 1971), in Rhopalopilia pallens PIERRE (BOUQUET, 1970) and in Opilia celtidifolia (GUILL. & PERR.) ENDL. (HAERDI, 1964, l.c sub 'Uses'; BOUQUET & DEBRAY, 1974; SHIHATA C.S., 1977). Alkaloid-like substances were also detected in the Madagas-can Rhopalopilia spp., in Rhopalopilia pallens and in Opilia celtidifolia, but confirmation of the presence of true alkaloids by isolation and characterization is still lacking. Saponins of the bark of Opilia celtidifolia have triterpenic sapogenins, i.e. oleanolic acid and hederagenin, according to SHIHATA C.S. (1977). This is in line with the saponins of African Olacaceae which have recently been shown to have mainly oleanolic acid and hederagenin as sapogenins.
— R. HEGNAUER.

Embryology

Detailed embryological investigations on members of this family are very rare. Only in Cansjera rheedii (SWAMY, 1960) and Opilia amentacea (SHAMANNA, 1955; SWAMY& RAO, 1963) the male and female gametophyte have been studied. In the tetrasporangiate anther a glandular tapetum with 2-4-nucleate cells is developed. The pollen grains are 2-celled when shed.

The anatropous ovule is unitegmic and has a much reduced nucellus. The nucellar tissue and the integument collapse in later stages of ovular development (therefore the ovules often have been described as ategmic). The chalazal megaspore of the linear tetrad develops into a Polygonum type embryo sac. A chalazal caecum grows down into the solid part of the gynoecium and so the embryo sac becomes U-shaped at maturity. The endosperm is cellular. Its chalazal chamber grows towards the base of the ovary forming a 1-nucleate haustorium which in Opilia amentacea reaches the pedicel of the flower. In Cansjera rheedii the haustorium is branched and secondary haustoria are developed. The embryogeny has not yet been studied.