Leea

Description

Trees, erect or creeping shrubs, scramblers, or herbaceous plants with a woody base; Leaves distichous, 1-foliolate, 3-foliolate, or 1- to 4-pinnate, usually imperfectly imparipinnate. Inflorescences in leaf-opposed cymes, lax or condensed by reduction of inflorescence branches, or peduncle, or both, erect or pendulous. Flowers bisexual, actinomorphic, 4- or 5-merous, rarely both in the same inflorescence. Ovary discoidal, 4-8-celled, each cell with 1 ovule; Fruit a berry, depressed-subglobose;

Distribution

A genus of 34 spp. of which 25 spp. are endemic in Malesia (with a few species extending to Queensland, Micronesia, and Fiji), 6 in SE. Asia (from Ceylon to S. China), 1 being widely distributed from tropical Africa and Madagascar through SE. Asia and Malesia to Taiwan and Micronesia, 1 sp. endemic in Madagascar and 1 sp. in the isle of Sao Tomé (W. Africa). .
The occurrence of L. philippinensis in the island of Botel Tobago, near Taiwan, is plant-geographically interesting as this is not collected in the mainland of Taiwan.
Fossil species have been described (fossil wood) from the Tertiary in Japan and Nagpur (India).

Morphology

Habit. Most species are smallish shrubs, some only woody at the base. Several may, however, attain some 10 m in height (L. aequata, L. aculeata) and four are even recorded to 15 m tall (L. angulata, L. indica, L. macropus, L. tetramera).

Two Malesian species are armed with spines (enations), viz L. aculeata (mostly on trunk and main branches) and L. angulata (from trunk to ultimate branches). (17').

Two species are occasionally recorded to be stilt-rooted, at least in large specimens, viz L. indica and L. macropus, while L. tetramera is said to have buttresses.

Seedlings. Leaf development is from 1- to 3-foliolate and pinnate. See for further details BURGER ().

Stipules. The stipular structures of the distant leaf are adpressed to form together a sheath surrounding the apex of the stem. As the latter continues growth the stipules are forced apart and drop off or remain as torn structures. There are basically two types, the long, narrow wing type which is usually semipersistent and, when caducous, leaving but a thin scar, and the obovate type which is rapidly caducous and leaves a broad triangular scar. Some intermediate forms are sometimes encountered. See , , and also and .

Anatomy

For general surveys also covering the older literature see . Selected references: .
The wood of Leea is characterized by diffuse solitary and grouped vessels with scalariform inter-vessel pits, large and simple vessel-ray pits and simple perforations. Scalariform perforations have been noted near the primary xylem of a few species only. The septate fibres are provided with minutely bordered pits. Parenchyma is scanty paratracheal, and the rays are usually of two distinct sizes. Broad heterogeneous rays are always present. The occurrence of raphides in the ray cells of most species is one of the outstanding characters. Solitary crystals may also occur.
The young stem is characterized by many raphide-cells also containing mucilage in the gland tissue, broad primary rays, fibre bundles near the primary phloem and superficial cork.
Characters of the leaves include globular glands, which possess a stoma more or less in apical position (), and of which the anatomy seems to differ slightly from the ‘classical’ pearl glands of Vitaceae sens. str. Simple uniseriate hairs also occur, and according to RACIBORSKI the petiole may be clad with ‘Ameisenfutterkörper’ (food-bodies for ants), the anatomy of which recalls Vitaceous pearl glands but which lack stornata. The stornata are recorded to be anomocytic, but are in need of further studies.
Raphides and large druses occur in the mesophyll in varying frequencies. The petiole is supplied with a closed ring of vascular tissue, whether or not with an extra dorsal ‘cortical’ bundle.
In spite of some wood anatomical differences, which may be interpreted as due to different habits (tree versus liane), Leea shares many characters with Vitaceae sens. str. in which it was formerly included. The wood anatomy bears also strong resemblance to that in Arthrophyllum of the Araliaceae, but this seems due to convergent evolution in the absence of other evidence supporting mutual affinities. — P. BAAS.

Taxonomy

CLARKE, l.c., has proposed a subdivision of series and sections, but I found them unreliable and refrain from any subdivision.
Some species appear to be very variable, while no tangible infraspecific subdivision can be made on the basis of herbarium specimens.
In many species the degree of pinnation of the leaf is exceedingly variable. Recognition of species differentiated solely on whether the leaves are 1-foliolate, 3-foliolate, or pinnate is abandoned. This is also the developmental sequence of leaves in growing seedlings. In such variable species flowering of plants with 1- or 3-foliolate leaves is considered to be precocious. These observations have led to a considerable reduction in the number of species.

Notes

Identification of fruiting material without stipules present on the material is difficult; good flowering material with adequate field notes is required. Distinguishing some forms of L. indica from L. guineensis without some knowledge of flower colour is difficult.

Phytochemo

Detailed chemical investigations are lacking. Most species of Leea seem to be non-toxic and mucilaginous (see for Indian species: ). Medicinal uses of roots, stems and leaves in India and Africa seem to be connected mainly with an abundance of phenolic constituents. Flavonols, p-hydroxybenzoic acid, syringic acid and gallic acid and flavan-3, 4-diols (= leucoanthocyanidins) were demonstrated to be present in leaves of L. guineensis G. DON (= L. coccinea PLANCH.), L. ìndica MERR. (= L. sambucina WILLD.), and L. rubra Bl. ex SPRENG. Tannins may also be present in appreciable amounts in some species. At present it is still impossible to appreciate the chemistry of Leeaceae from a systematic point of view, because too little information is available. The type of polyphenolic constituents known to be present and the fact that oxalate of lime occurs in the form of raphids, however, point to an affinity with Vitaceae (for references see: ). — R. HEGNAUER.

Citation

LINNÉ - in Mantissa. 1767: 17, 124
CLARKE - in J. Bot. 1881
GAGNEP. - in Bull. Soc. Bot. Fr. 1910
SUESSENGUTH - in E. & P., Nat. Pfl. Fam., ed. 2, 20d. 1953: 382
RIDSDALE - in Blumea. 1974: with full synonymy and typification.
DENNST., Schlüssel Hort. Mal. 1818: 13, 27

Synonymy

Leea VAN ROYEN ex LINNÉ in Syst. Nat., ed. 12 2: 627. 1767
  • Nalagu ADANS. in Fam. PL 2: 445, 581. 1763
  • Aquilicia LINNÉ in Mantissa 2: 146, 211. 1771
  • Otillis GAERTN. in Fruct. 1: icon. tab. 57 f. 7. 1788
  • Ticorea BLANCO, Fl. Filip.: 85. 1837

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