Hernandiaceae

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Hernandiaceae

Description

Trees, shrubs, or woody climbers, with bisexual or unisexual flowers. Leaves alternate or spirally arranged, petiolate, without stipules, simple, lobed or unlobed, or pal- mately compound, margin entire. Inflorescences usually axillary, much-branched, compound cymes, sometimes corymbose; with or without bracts. Stamens 3-7 in a single whorl opposite the tepals, or in a double whorl inserted opposite the outer tepals; filaments with two basal glands, or with one dorsal gland, or without glands; anthers 2-locular, dehiscing with 2 lateral or apical valves; interstaminal staminodes present or absent. Ovary inferior, 1-locular; ovule 1, pendulous; style simple, in male flowers absent or reduced; stigma discoid and oblique or capitate. Fruits dry, indehiscent, nut- or drupelike, unwinged and enclosed by inflated, fleshy, expanded cupule (Hernandia) or not, or with 2-4 lateral wings (Illigera) or with 2 apical wings (Gyrocarpus). Seed 1, without endosperm; embryo straight; cotyledons large.

Distribution

African-Asian-Malesian region: present Northern America: Southern America:
A family of 4 genera, Gyrocarpus (3 species) and Hernandia (24 species) both tricentric-tropical, Illigera (c. 20 species) in the African-Asian-Malesian region, and Sparattanthelium (13 species) in Central America and Mexico.

Pollination

No observations are recorded, but the flowers of Hernandia and Illigera are often reported to be fragrant and the staminal appendages of Illigera seem to function as nectaries; the pollen grains of both genera are large and sticky. These characters suggest that the Hernandia and Illigera species may be entomogamous. The flowers of Gyrocarpus and Sparattanthelium are small and numerous, especially the male ones. They are not fragrant and pollen grains are small and powdery; these genera are possibly anemogamous.

Dispersal

All Hernandiaceae have more or less drupaceous fruits which are winged in Illigera and Gyrocarpus. The fruits may be drifted by the wind over short distances. Fruits of G. americanus and H. nymphaeifolia have been observed drifting in the sea, and can retain their buoyancy for several months; in both species the buoyancy is apparently effected by the spongy testa.

Taxonomy

The genera here recognized in Hernandiaceae have a checkered taxonomic history. Kubitzki (1969) comprehensively dealt with it. Most authors agree upon a relation with Lauraceae. Gyrocarpus is often placed in a separate family, Gyrocarpaceae. Pax (1889) established Hernandiaceae in the present sense, with four genera, divided into two subfamilies, Hernandioideae (Hernandia and Illigera) and Gyrocarpoideae (Gyrocarpus and Sparattanthelium)', this was followed by Kubitzki (1969). See also page 761.

Uses

Some Hernandia species and Gyrocarpus americanus produce a rather soft and not very valuable wood, used for making canoes and as timberwood. The oil of the seeds of Hernandia nymphaeifolia is used locally as lampoil, but is of inferior quality (Heyne 1950).

Phytochemo

Several reviews of the chemistry of the family are available (Hegnauer 1966, 1989; Kubitzki 1969; Pernet 1971; Gottlieb et al. 1993). It has to be stressed, however, that thorough chemical investigations are restricted to a few species of Illigera and Hernandia and to alkaloids of Gyrocarpus americanus and Sparattanthelium uncigerum. A summary of presently known chemical data follows.

Kubitzki (1969) investigated phenolics in hydrolized leaf extracts and reported genus- characteristic patterns. Kaempferol, quercetin and its 3'-methylether isorhamnetin were detected in 14 taxa of Hernandia and occurred erratically and usually in trace amounts only in Illigera (16 taxa investigated), Gyrocarpus americanus and jatrophifolius and Sparattanthelium (12 taxa). Vitexin-like C-glycoflavones were present in Hernandia albiflora and in all taxa of Illigera and in trace amounts in 7 taxa of Sparattanthelium. Proanthocyanidins were present in large to moderate amounts in 7 taxa of Hernandia, 14 taxa of Illigera, but were totally lacking in Gyrocarpus and Sparattanthelium. Ferulic and sinapic acids were detected in trace to moderate amounts in practically all taxa of Hernandia, Gyrocarpus and Sparattanthelium and were lacking in Illigera. The apparent absence of the wide-spread p-coumaric and caffeic acids and the greatly reduced or totally suppressed production of flavonols and flavones in Gyrocarpus and Sparattanthelium represent notable features of phenolic metabolism of Hernandiaceae. Concerning flavonoids it should not be forgotten, however, that screening procedures of the type applied by Kubitzki and making use of herbarium material are useless for the detection of flavanones and flavanonols (= 2,3-dihydroflavonols). Indeed, prenylated and/or geranylated flavanones, the nymphaeols -A to -C, were isolated from H. nymphaeifolia (Presl) Kubitzki (= H. peltata; Japanese name 'Hasunoha-giri') (Yakushijin et al. 1980).

One class of compounds is relatively well known from the family. Alkaloids have been detected in all four to five genera. They belong to the phenylalanine-tyrosine- derived family of isoquinoline alkaloids and are represented by the benzylisoquinoline-, aporphine-, oxo-aporphine-, N,N-dimethylaminoethyl-phenanthrene-types and by di- meric derivatives of these monomers. A strange compound is 3-cyano-4-methoxy- pyridine from H. nymphaeifolia (Yakushijin et al. 1980); as yet its biogenesis is not known.

Lignans seem to occur frequently in stems, leaves and seeds of many species of Hernandia. Hitherto they were not yet isolated from representatives of other hernandiaceous genera. Known Hernandia lignans belong to several types: furofuranoid-, tetralin (= tetra- hydronaphthalene)-, naphthalene- and bibenzylbutanolide-types; examples (isolated from Hernandia taxa) are epimagnolin, podophyllotoxin, 1,2,3,4-tetradehydrodehydroxy- podophyllotoxin and podorhizol. Two new lignans, dimethylmatairesinol and 5'-meth- oxypodorhizol, were isolated from seeds of H. ovigera\ seeds of this taxon yielded eleven lignans till today (Tanoguchi et al. 1991). Neolignans were not yet detected in the family.

Oil cells of the magnolioid type are wide-spread in the family; they occur mainly in leaves and in the primary cortex and pith of stems (Kubitzki 1969) and perhaps also in roots and fruits. Their presence indicates that essential oils should be of common occurrence. However, only a few investigations of essential oils are reported in literature. Hernandia peltata yielded essential oils from roots, stems and fruits in Madagascar; the wood oil (2%) had perillaldehyde as main compound and myrtenal, cineol and limonene as additional monoterpenes. The smell of perillaldehyde is described in literature as cuminlike or as camphoraceous (Gildemeister & Hoffmann 1959,1963; Guenther 1949; Weber 1974). Perillaldehyde is also the principal constituent of the essential oil of bark and twigs of Madagascan H. voyroni (Weber 1974).

Metcalfe (1987) stated "oil cells have been reported in all genera and species and they are sometimes accompanied by mucilage cells." The last-mentioned feature reminds of Lauraceae and explains observations made by Greshoff that the bark of H. ovigera and H. sonora is mucilagineous.

Hernandiaceae have seeds without endosperm (all ?) containing embryos with large cotyledons. Some hints can be found in literature that several species store large amounts of fatty oils in their seeds, but exact information is scarce. According to Netolitzki (1926) Hernandiaceae (which?) store fatty oils, protein bodies and starch in cotyledons. Corner (1976) stressed the fact that hitherto only seeds of Hernandia were studied in some detail and drew attention to similarities between seeds of Hernandia and those of Myristi- caceae.

Usually affinities of Hernandiaceae with Lauraceae and Monimiaceae are assumed. As far as chemical data are available they do not contradict such a relationship.
1. R. Hegnauer

Citation

Ng - in Tree Fl. Malaya. 1973: fig.
Blume - in Kubitzki et al., The families and genera of vascular plants 2, X. 1993: 334.
A.C.Sm. - in Fl. Vit. Nov. 1981: fig.
Backer & Bakh. f. - in Fl. Java. 1963
Du Puy & Telford - in Fl. Austral. 1993: fig.
Kubitzki - in Fl. Camb., Laos & Vietnam. 1970: fig.
Croft - in Handb. Fl. Papua New Guinea. 1981: fig.
Kubitzki - in Bot. Jahrb. 1969: 51 fig.