Taxonomic History

The genus was formally established by Linnaeus in his Systema Naturae (1759) with the publication of the protologue of I. anisatum L. Numerous new species names were subsequently introduced, although no attempt was made to comprehensively revise the taxonomy of the genus until Smith (1947) undertook his monograph. Smith recognized 42 species, with a disjunct distribution in eastern North America, Mexico, and the West Indies (5 species) and eastern Asia (37 species). Several regional revisions have subsequently been published (Saunders, 1995, 1997; Zhang, 1996).

Smith (1947) classified the genus into two sections: sect. Illicium (under the synonym sect. Badiana Spach) and sect. Cymbostemon (Spach) A.C. Sm. The former section is characterized by thin, membranous inner tepals that are somewhat lax at anthesis and are narrowly oblong, ligulate,

FIGURE 2.1 Fruit of Illicium stapfii Merr. from Borneo: The follicetum is dry and is dehiscing along the adaxial margin, exposing the seed inside. Photograph © Richard M.K. Saunders.
FIGURE 2.2 Seed of Illicium stapfii Merr. Photograph © Richard M.K. Saunders. © 2004 by CRC Press LLC
FIGURE 2.3 (see color insert following page 22) Illicium anisatum L., with elongated tepals (typical of sect. Illicium). Reproduced from Hooker (1842: pl. 3965). Photograph © Royal Botanic Gardens, Kew.
FIGURE 2.4 (see color insert following page 22) Illicium verum Hook. f., with short tepals (typical of sect. Cymbostemon). Reproduced from Hooker (1888: pl. 7005). Photograph © Royal Botanic Gardens, Kew.

or lanceolate in shape (Figure 2.3). In contrast, sect. Cymbostemon possesses carnose to papyraceous inner tepals that are never lax and that are usually ovate to suborbicular in shape (Figure 2.4). Keng (1965) suggested that tepal shape was a significant taxonomic character because it reflected more fundamental differences in floral vasculature; the significance of the vascular distinctions are unclear, however, as Saunders (1995) has indicated that a variety of different vascular arrangements are found in the tepals of several species of sect. Cymbostemon. Species of sect. Cymbostemon invariably have trisyncolpate pollen (with three furrows that fuse over the distal pole), whereas species of sect. Illicium typically have trizonocolpate pollen (with three furrows that do not fuse over the distal pole) (Erdtman, 1952; Ikuse, 1956; Wodehouse, 1959; Hayashi, 1960; Walker, 1976; Lieux, 1980; Lin, 1989; Liu and Yang, 1989; Saunders, 1995). Although the palynological data therefore broadly corroborate the sectional classification, the correlation is not absolute, as I. floridanum Ellis possesses trisyncolpate pollen (Wodehouse, 1959; Lieux, 1980) despite being assigned to sect. Illicium on the basis of floral morphology. This incongruence is particularly significant because Illicium is otherwise extremely stenopalynous.

Smith's (1947) infrageneric classification of the genus has been widely accepted. The only publication to offer an alternative to this classification (Zhang, 1996) elevated sections Illicium and Cymbostemon to the subgeneric level. Zhang furthermore recognized two sections within subgenus Illicium based on foliar venation differences, namely, sect. Illicium and sect. Impressicosta Y.-W. Law and Q. Lin.

Hao et al. (2000) recently published a phylogenetic analysis of the genus based on sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA. They found that the two sections recognized by Smith (1947) were unnatural, and that the ITS phylogeny was congruent with the palynological data.

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