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FOC | Family List | FOC Vol. 5 | Urticaceae

12. Boehmeria Jacquin, Enum. Syst. Pl. 9: 31. 1760.

苎麻属 zhu ma shu

Chen Jiarui (陈家瑞 Chen Chia-jui); Ib Friis, C. Melanie Wilmot-Dear

Trees small, shrubs, subshrubs, or perennial herbs, without stinging hairs. Leaves alternate or opposite; stipules deciduous, intrapetiolar, free or rarely connate at base; leaf blade 3-veined, margin dentate, rarely 2- or 3-lobed; cystoliths punctiform. Inflorescence an axillary glomerule, on normal leafy stems or on specialized, slender, mostly axillary, occasionally terminal, shoots, these unbranched and spikelike to branched and panicle-like, mostly unisexual, less often bisexual. Flowers unisexual (plants monoecious or dioecious); bracts and bracteoles small, scarious. Male flowers: perianth (3 or)4 or 5-lobed or parted, segments valvate; stamens (3 or)4 or 5; filaments inflexed in bud; rudimentary ovary clavate or subglobose. Female flowers: perianth tubular, usually compressed, apex 2-4-toothed, in fruit sometimes enlarged and dilated into 2 acute angles or wings; staminodes absent. Ovary included; stigma filiform, on a style, pilose on 1 side, usually persistent for some time; ovule orthotropous. Achene not lustrous, enclosed by marcescent perianth, Seed with endosperm; cotyledons elliptic or ovate.

About 65 species: tropical, subtropical, and rarely temperate regions; 25 species (six endemic) in China.

1 Glomerules all axillary on normal leaf branches; male flowers 4-merous; leaves alternate.   1 B. glomerulifera
+ Glomerules all or partly arranged on specialized slender flowering branches; male flowers (3-)4-5-merous; leaves alternate or opposite.   (2)
2 (1) Male glomerules in axils of foliage leaves, female glomerules on specialized long spikelike shoots in terminal and subterminal axils; male flowers 4-5-merous, pedicel 2-5 mm.   3 B. zollingeriana
+ Glomerules all arranged on specialized slender flowering shoots, rarely simply axillary; male flowers 4-merous, pedicel very short to absent.   (3)
3 (2) Flowering shoots with tuft of foliage leaves at apex.   (4)
+ Flowering shoots without tuft of leaves at apex (except rarely in B. silvestrii).   (5)
4 (3) Leaves not lobed, apex acuminate or caudate.   4 B. clidemioides
+ Leaves lobed, apex cuspidate.   5 B. umbrosa
5 (3) Flowering shoots branched; leaves alternate or opposite.   (6)
+ Flowering shoots usually unbranched, sometimes loosely branched at base; leaves opposite, seldom alternate in distal part of stem (only in B. allophylla and B. tricuspis).   (8)
6 (5) Flowering shoots in pairs; leaves alternate, abaxially often white tomentose (or strigose in var. tenacissima); achene long stipitate at base.   2 B. nivea
+ Flowering shoots solitary; leaves opposite, glabrous or sparsely strigillose abaxially; achene base obtuse or cuneate.   (7)
7 (6) Leaf blade elliptic ovate, apex acuminate; flowering shoots with irregular second order branching; achene base narrowly cuneate.   20 B. polystachya
+ Leaf blade ovate-orbicular to suborbicular, apex abruptly caudate; flowering shoots with simple, spikelike branches only; achene base rounded.   21 B. conica
8 (5) Leaf blade often 3-cusped or 3-lobed, rarely 5-lobed at apex.   (9)
+ Leaf blade not divided at apex.   (12)
9 (8) Leaf blade often papery, 7-15(-22) cm wide, teeth 10-20 mm.   (10)
+ Leaf blade herbaceous, 1-8(-13) cm wide, teeth less than 10 mm.   (11)
10 (9) Leaf blade ovate or broadly ovate, apex sometimes inconspicuously tricuspidate, base often broadly cuneate; spikes or rarely few branched at base.   15 B. japonica
+ Leaf blade oblate to 5-angled or oblate to orbicular-ovate, apex often 3-lobed, base often truncate or subcordate; spikes well branched into subpanicle.   16 B. tricuspis
11 (9) Leaves all opposite, apex 3- or 5-cuspidate, base broadly cuneate to subtruncate, teeth 2-10 mm, sparsely strigose or subglabrous on both surfaces.   17 B. silvestrii
+ Leaves alternate on upper stems, opposite on lower stems, apex tricuspidate, base broadly cuneate, teeth 1-2.5 mm, long appressed hirsute adaxially, pubescent abaxially.   19 B. allophylla
12 (8) Leaf blade lanceolate or linear-lanceolate.   (13)
+ Leaf blade ovate or suborbicular, rarely sublanceolate (in B. hamiltoniana).   (16)
13 (12) Leaf blade herbaceous, lanceolate, smooth adaxially, apex caudate or acuminate; female spikes of usually distant glomerules, often branched at base, straight; achene stipitate or very shortly so.   (14)
+ Leaf blade thickly papery, linear-lanceolate, often strongly rugose adaxially, apex tapering to acuminate; female spikes of congested glomerules, simple, nodding; achene long stipitate.   (15)
14 (13) Leaf blade apex entire, margin dentate; flowering shoots unbranched or with a few short irregular branches near base; achene almost without stipe.   10 B. formosana
+ Leaf blade apex serrulate, margin finely serrulate; female flowering shoot dichotomously forked at lowermost glomerule; achene stipitate.   23 B. ingjiangensis
15 (13) Leaf blade 14-29 × 2.2-5.5 cm, glabrous or glabrescent adaxially, teeth revolute; female spikes 6-32 cm; perianth tube of female flower 1.6-2.2 mm, apex rounded.   24 B. penduliflora
+ Leaf blade 5-24 × 2-6.4 cm, densely appressed strigillose adaxially, teeth flattened; female spikes 4-18 cm; perianth tube of female flower 1-1.5 mm, apex attenuate.   25 B. densiflora
16 (12) Flowering shoots branched at base.   (17)
+ Flowering shoots unbranched.   (27)
17 (16) Shrubs.   (18)
+ Herbs perennial or subshrubs.   (21)
18 (17) Leaf blade elliptic ovate; flowering shoots with irregular second order branching.   20 B. polystachya
+ Leaf blade oblong, narrowly ovate or oblanceolate; flowering shoots with simple, spikelike branches only.   (19)
19 (18) Branches glabrous; spikes very slender, to 26 cm.   11 B. hamiltoniana
+ Branches strigose; spikes straight, 4-10 cm.   (20)
20 (19) Branches dark purplish brown; leaf blade oblong or oblong-lanceolate, apex acuminate, tip denticulate; inflorescence unbranched.   8 B. lanceolata
+ Branches light brown; leaf blade elliptic, apex acuminate, tip entire; inflorescence with shorter branches from base.   9 B. lohuiensis
21 (17) Leaf margin coarsely 7-14-dentate, teeth gradually larger distally.   15 B. japonica
+ Leaf margin dentate, denticulate, or serrulate, all regular.   (22)
22 (21) Leaf blade herbaceous or rarely membranous, suborbicular or orbicular-ovate.   (23)
+ Leaf blade usually herbaceous or papery, ovate or oblong.   (25)
23 (22) Leaf base rounded, patent pubescent abaxially.   6 B. macrophylla
+ Leaf base truncate or cordate, appressed strigose abaxially.   (24)
24 (23) Leaf blade 6.5-19 × 6-17.5 cm; spikes of distant glomerules to 40 cm.   13 B. dolichostachya
+ Leaf blade 5-9.4 × 5-8 cm; spikes of congested glomerules to 5.5 cm.   14 B. densiglomerata
25 (22) Leaf blade papery, oblong, apex denticulate.   8 B. lanceolata
+ Leaf blade usually herbaceous, ovate or narrowly ovate, apex entire.   (26)
26 (25) Leaf margin dentate; achene verrucose.   10 B. formosana
+ Leaf margin denticulate or serrulate; achene smooth.   6 B. macrophylla
27 (16) Leaf blade ovate-rhombic or rhombic, margin coarsely 3-9-dentate.   18 B. spicata
+ Leaf blade ovate or suborbicular, margin serrulate, crenulate, or denticulate.   (28)
28 (27) Leaf blade suborbicular.   (29)
+ Leaf blade ovate, rarely also lanceolate (in B. hamiltoniana).   (34)
29 (28) Leaf margin coarsely 9-14-dentate, teeth gradually larger distally.   15 B. japonica
+ Leaf margin subregularly dentate, denticulate, or serrulate.   (30)
30 (29) Branchlets densely yellowish tomentose; leaf blade tomentose to densely pubescent on both surfaces.   12 B. tomentosa
+ Branchlets strigose; leaf blade strigose adaxially.   (31)
31 (30) Leaf blade patent pubescent abaxially.   (32)
+ Leaf blade strigillose abaxially.   (33)
32 (31) Leaf blade sparsely puberulent abaxially.   6 B. macrophylla
+ Leaf blade densely pubescent abaxially.   13 B. dolichostachya
33 (31) Herbs perennial to 0.5 m tall; leaf blade 5-9.4 × 5-8 cm; female or bisexual spikes of congested glomerules 2-5 cm.   14 B. densiglomerata
+ Subshrubs or shrubs to 3 m tall; leaf blade 6.5-19 × 6-17.5 cm; female spikes of distant glomerules 9-40 cm.   13 B. dolichostachya
34 (28) Branches glabrous; leaf blade narrowly ovate to lanceolate, margin finely crenulate throughout; spikes very slender, to 26 cm.   11 B. hamiltoniana
+ Branches strigose; leaf blade ovate or narrowly ovate, margin dentate, denticulate, or serrulate, with entire tip; spikes usually less than 26 cm.   (35)
35 (34) Female spikes 0.8-2 cm; plants 0.4-0.6 m tall.   7 B. pilosiuscula
+ Female spikes 4-20 cm; plants 0.7-3.5 m tall.   (36)
36 (35) Shrubs or small trees; petiole to 1.2 cm; female inflorescences often in groups of 2-4; female perianth tube patent-puberulent all over.   22 B. siamensis
+ Herbs perennial or subshrubs; petiole to 6 or 13 cm; female inflorescences solitary; female perianth tube strigillose on shoulder.   (37)
37 (36) Leaf teeth 6-20 mm, gradually larger distally.   15 B. japonica
+ Leaf teeth 2-5 mm, regular.   (38)
38 (37) Leaf narrowly ovate or oblong-ovate, glabrous or subglabrous adaxially; achene verrucose.   10 B. formosana
+ Leaf ovate, often rugose, strigose adaxially; achene smooth.   6 B. macrophylla

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