Schisandraceae

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Schisandraceae

Description

Woody vines, monoecious or dioecious. Leaves alternate or ± clustered, exstipulate, petiolate; lamina simple. Flowers generally solitary and axillary to leaves on ultimate branches, or in axils of fugacious bracts near base of ultimate shoots, occasionally in pairs or in clusters of up to 8, unisexual, hypogynous, few to numerous parts generally spirally arranged, pedicellate. Fruit an aggregate of berries; receptacle ellipsoid to elongate; berries with carnose pericarp. Seeds 1-5, rarely more, ventrally attached or pendulous, laterally flattened, with copious oily endosperm.

Distribution

Asia: present south-eastern North America: present
The Schisandraceae have a disjunct distribution, occurring in Asia (c. 46 species, with a centre of diversity in continental Asia) and in south-eastern North America (1 species).

Morphology

Inflorescence structure is discussed in detail by Weberling (1988). Many species produce solitary flowers from the leaf axils, on branches which bear numerous scale-like leaves (presumably acting as bud scales) at the base of the axis. Other species produce flowers in the axils of fugaceous bracts; the two lowermost bracts (prophylls) bear vigorous buds that enable continued growth. Transitional forms also occur.

The flowers of the Schisandraceae are relatively primitive structurally as in the Illiciaceae, with spirally arranged floral organs and perianth segments that do not form distinct sepals and petals. A major distinction between the Illiciaceae and the Schisandraceae, however, is that the latter family is monoecious (although possibly dioecious in some species), whereas the Illiciaceae possess hermaphrodite flowers.

The female flowers of the Schisandraceae are structurally primitive, with numerous (12-300) free conduplicate carpels spirally arranged around the receptacle, with stig- matic crests that lack a distinct style (although sometimes with an essentially unvascular- ised 'pseudostyle'). The two genera in the family are largely distinguished on the basis of the shape of the receptacle in the female flower (and consequently the shape of the aggregate fruit) and the structure of the stigmatic crest; the taxonomic significance of this is discussed further below.

The male flowers show great variation in androecial anatomy, although this cannot be used taxonomically at the generic level. The more primitive species in both genera in the family possess numerous stamens that are united by fusion of the base of the filaments. Many of the more advanced members of the family show an evolutionary change that is superficially parallel, with aggregation of stamens in compact (sub)globose heads; a distinction can be made between the two genera, however, as the stamens are either fused together to form a carnose mass, or else are tightly compressed but free. Other members of the family show an evolutionary reduction in the number of stamens, with as few as four in one species. The variation in the androecial structure is discussed in greater detail under the generic treatments.
A. Weberling, F. in Taxon 37. 1988

Anatomy

The most comprehensive discussions of the vegetative structure of the family are by Bailey & Nast (1948) and Metcalfe (1987).

The leaves of the Schisandraceae frequently show marginal denticulation, although this is variable. Characteristic features of the leaf anatomy include: epidermal cells with undulating or sinuous anticlinal walls; and mixed paracytic and laterocytic stomata (Bara- nova 1983), with cuticular intrusions between the ends of the two members of each pair of guard cells (but with smaller intrusions than observed in the closely related family Illiciaceae). The nodes are unilacunar, with three leaf traces.
The internodal regions of the stem have either a eustelic or a siphonostelic vascular arrangement. The secondary xylem (Bailey & Nast 1948; Metcalfe 1987) is also variable, ranging from a relatively primitive dense to specialised highly porous arrangement. The more primitive type is characterised by narrow vessel members with scalariform perforation plates; thick-walled tracheids; multiseriate rays with intervening high-celled uniseriate rays; and scanty diffuse and abaxial paratracheal wood parenchyma. The more advanced type is characterised by broad vessel members with a single large lacuna; large, thin-walled profusely pitted tracheids; mostly uniseriate rays; and abundant paratracheal wood parenchyma. The phloem contains numerous elongated or cambiform elements with stratified mucilaginous contents. The sclerenchyma is linear, elongated and fibrelike.
B. Bailey, I.W. & C.G. Nast in J. Arnold Arbor. 29. 1948, C. Baranova, M. in Brittonia 35. 1983, D. Metcalfe, C.R. - in Anatomy of the Dicotyledons. 1987

Taxonomy

The most recent comprehensive taxonomic revision of the family is by A.C. Smith (1947, cited earlier), who accepted two genera, Schisandra with 25 species and Kadsura with 22 species. The distinction between the two genera is largely based on gynoe- cial and fruit characters. Kadsura is characterised by female flowers with obovoid, sub- clavate or ellipsoid receptacles that are only slightly longer than wide, and which remain comparatively short after fertilisation; the aggregate fruits are consequently subglobose clusters of berries. In marked contrast, Schisandra is characterised by female flowers with cylindrical or conical receptacles that are markedly longer than wide, and which become highly elongated in the fruits. Differences also exist in relation to the stigmas, which are broad and often peltate in Kadsura, but narrow and subulate in Schisandra. The generic distinctions are not reflected in androecial structure, however, which makes the identification of specimens that bear only male flowers problematic. This difficulty is particularly acute with regard to species belonging to the more primitive sections Cos- baea of Kadsura and Pleiostema of Schisandra, which tend towards the hypothetical ancestral type. This problem is obviated within Malesia, however, as none of the Kadsura species described in the region belong to sect. Cosbaea.

Cytology

The base chromosome number of the family is regarded as x = 7, 13. As this base number is also shared by the closely related family Illiciaceae, Ehrendorfer et al. (1968) have suggested that these two families (collectively forming the order Illiciales) diverged from the basic Magnolialean stock and extinct precursors with x = 7 by dysploid reduction from the palaeotetraploid level of 2x = 14 to 2x = 13.
E. Ehrendorfer, F. in Taxon 17. 1968

Uses

The uses of both Kadsura and Schisandra are discussed under these genera.

Phytochemo

See the relevant chapter in the treatment of Illiciaceae (this issue, p. 175).

Embryology

Microsporogenesis (Hayashi 1960; Kapil & Jalan 1964; Vijayaraghavan & Dhar 1975), megasporogenesis and embryology (Yoshida 1962; Hayashi 1963; Kapil & Jalan 1964; Swamy 1964; Davis 1966) have been studied in detail for several species of Schisandra and Kadsura. The tapetum is glandular and binucleate, pollen mother cell divisions are simultaneous and the pollen grains are 2-celled when the anther dehisces. The development of the embryo sac appears to be of the Polygonum type, and the development of the embryo is of the Asterad or Onagrad type.
F. Davis, G.L. - in Systematic embryology of Angiosperms. 1966, G. Hayashi, Y. in Sci. Rep. Tohoku Univ., IV (Biol.) 26. 1960, H. Hayashi, Y. in Sci. Rep. Tohoku Univ., IV (Biol.) 29. 1963, I. Kapil, R.N. & S. Jalan in Bot. Not. 117. 1964, J. Swamy, B.G.L. in J. Ind. Bot. Soc. 43. 1964, K. Vijayaraghavan, M.R. & U. Dhar in J. Arnold Arbor. 56. 1975, L. Yoshida, O. in J. Coll. Arts Sci. Chiba Univ. 3. 1962

Citation

Backer & Bakh. f. - in Fl. Java. 1964: 98
G. Don - in Gen. Hist. 1831: 'Schizandriaceae'
A.C. Sm. - in Sargentia. 1947
Ridl. - in Fl. Malay Penins. 1922: 'Schizandraceae'