Mesua L. emend Kosterm.

Shrubs or middle-sized trees, sometimes larger. Branches often slender, glabrous. Leaves opposite, polymorphic, lanceolate, entire, petiolate, coriaceous, pellucid-dotted, shiny above, often pruinose or glaucous beneath; midrib conspicuous, lateral nerves slender, often obsolete, polygonaly reticulate; foliar crystals subsimple, geniculate. Flowers solitary, paired, subfasciculate to fasciculate or in panicles, axillary or terminal, bisexual or polygamous, pretty, sessile or pedicellate, variable in size. Sepals 4, usually outer pair smaller than inner, decussate, imbricate, usualy accrescent in fruit. Petals 4, large, alternate with sepals, imbricate. Stamens numerous, hypogynous; filaments filiform, free or connate at base; anthers variously shaped, usually linear-oblong to oblong, basifixed, 2-loculed, connective narrowly marginate, dehiscing at the top or by lateral vertical clefts. Ovary uni-or bilocular, sometimes incompletely bilocular; ovules 2 in each locule, erect, anatropous; style 1, subulate or filiform, slightly flexuous; stigma peltate, irregularly patelliform, obscurely bilobed, incised or 4-fid. Fruits fleshy, drupa-ceous or capsular nuts, encased by lignified enlarged sepals, 1 - 2-loculed, indehiscent or dehiscent, ultimately dehiscing into 2 - 4-valves. Seeds 1 - 4, exarillate, erect, often mutually pressed in an obtuse angle, exalbuminous; testa slender, fragile, hilum linear, micropyle inconspicuous.

Tropical Asia and Indo-Malesia to Australia (Queensland); ca 40 species; 6 in India, of which 3 are endemic.

Literature. MAHESHWARI, J.K. (1964). Taxonomic studies on Indian Guttiferae. II. The genus Mesua Linn. Bull. Bot. Surv. India 5: 335 - 343 t. 1 - 4. KOSTERMANS, A.J.G.H.(1969). Kayea Wall. & Mesua L in Reinwardtia 7: 425 - 431. STEVENS, P.F. (1986). Mesua ferrea became M. nagaaarium but has to be called M. ferrea again (Clusiaceae). Taxon 35: 352 - 354.

Notes. Common in tropical forests; often forming consociations. The genus Kayea Wallich (Pl. Asiat. Rar.3: 4, t. 210. 1832) considered congeneric here is generally distinguished from Mesua by its unilocular ovary with 4 ovules, single style with a 4-fid apex and 1-seeded drupes, while Mesua has a bilocular ovary with 4 ovules and single style with a peltate stigma. Kostermans (Reinwardtia 7: 425. 1969) has observed many possible intergradations between the two and merged them.

KEY TO THE SPECIES

1a. Lateral veins of leaves distinct, arched; flowers less than 4 cm across; fruits indehiscent

2

b. Lateral veins of leaves very fine, almost invisible, straight, nearly parallel; flowers more than 4 cm across; fruits dehiscent

4

2a. Leaves ovate to elliptic-lanceolate; flowers small, (ca 7 - 8 mm across), on short branches in 8 - 15 cm long panicles

1. Mesua assamica

b. Leaves oblong to lanceolate: flowers large (more than 1 cm across), in clustered racemes or lax panicles

3

3a. Petioles more than 1 cm long; flowers 2 - 2.5 cm across in terminal, ca 15 cm long panicles; ovary not ridged

3. Mesua fioribunda

b. Petioles less than 1 cm long; flowers 1 - 1.5 cm across, in ca 6.5 cm long racemes, crowded at tips of branehlets; ovary distinctly ridged

4. Mesua manii

4a. Branehlets pendulous; leaves green beneath, scarcely glaucous or not pruinose, ovate or elliptic-oblong; flowers ca 4.5 cm across

5. Mesua pulchella

b. Branehlets patent or slightly pendulous; leaves white, glaucous or pruinose beneath, lanceolate, lanceolate-oblong or linear-oblong; flowers more than 4.5 cm across

5

5a. Leaves 16 - 30 x 3 - 11 cm; flowers and fruits sessile; flowers comparatively large, more than 10 cm across, surrounded by 2 - 3 large, persistent, adpressed bracts and bracteoles

6. Mesua thwaitesii

b. Leaves 5 - 18 x 1 - 5 cm; flowers and fruits distinctly pedicelled; flowers comparatively smaller, up to 10 cm across, ebracteate and ebracteolate

2. Mesua ferrea

List of Lower Taxa