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Plants of Taiwan

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    台灣植物誌 第二版  Flora of Taiwan, 2nd edition    Vol. 4

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    台灣植物誌第二版  Flora of Taiwan, 2nd edition  4: 826

    6. AMBROSIA L. ޯ

    Coarse herbs, perennial or annual. Leaves opposite or alternate, usually lobed or dissected. Florets greenish, inconspicuous. Heads unisexual, without ligulate florets, of 2 kinds, staminate heads conical, in terminal racemes, involucre flattish, of bracts 7-12, united, florets 5-20, anthers nearly distinct; pistillate heads ellipsoid to obovoid, with 4-8 small tubercles (representing tips of connate bracts) at apex, 1-few together, sessile in axils of leaves below staminate racemes; styles elongate, branches exserted. Achenes ovoid.

    About 40 species in the New World. One American species widely naturalized in eastern Asia.


    1. Ambrosia artemisiifolia L., Sp. Pl. 988. 1753; Hatusima, Fl. Ryuk. 2nd. Ed. 896. 1975.
    ޯ ( FG) Pl. 382

    Ambrosia elatior L., Sp. Pl. 987. 1753; Hatusima, Fl. Ryukyus 600. 1971; Hsu, Taiwania 18(1): 65. 1973; Li, Fl. Taiwan 4: 780. 1978.

    Erect annuals; stems 30-100 cm tall, branched, soft pubescent. Leaves 3-11 cm long, bi- or tri-pinnatifid, upper surface slightly pubescent, lower surface pubescent. Racemes terminal, slender, staminate heads above, nodding; pistillate heads few, on lower part or raceme; involucre bracts connate, pubescent, glandular. Involucre and achenes united into a hard false fruit with wart-like papillae.

    Native of North America; a polymorphic weed widely naturalized in the warmer parts of the world. Taiwan, a widely naturalized weed along freeways, open construction sites and waste places in lowlands.

    TAIPEI: Shihmen, Ho 291. HSINCHU: Chupei, Hsinkang Village, Peng 15231; Lienhuassu, Kao106. NANTOU: Wushe, Peng 2309.


    7. ANAPHALIS DC. ţ­

    Perennial erect herbs, whitish woolly or tomentose, often stoloniferous, dioecious or polygamo-dioecious. Leaves alternate, entire, linear to lanceolate or oblong, often decurrent. Heads small, inflat-topped corymbs. Involucre oblong to campanulate, bracts scarious, imbricated in 5-8 series, often whitish, outer bracter shorter, outermost woolly. Receptacles mostly convex, not paleaceous. Corolla of outer florets with filiform, 2- to 4-dentate, style undivided, anthers sagittate at base. Corolla of central florets tubular, 5-toothed, functional staminate; style bifid. Achenes very small, oblong. Pappus bristles 1 series, slender, scabrid, free, caducous.

    About 110 species mainly in Asia, a few in North America; about four species in Taiwan.


    KEY TO SPECIES

    1. Heads14-17 mm across, 1 cm long; leaves usually shorter than head ............................. 3. A. nepalensis
    1. Heads 4-10 mm across, 0.4-0.6 cm long; leaves longer than head.
    2. Leaves distinctly decurrent ....................................................................... 4. A. royleana
    2. Leaves not distinctly decurrent.
    3. Heads 3-5, at apex of stems; leaves oblong-obovate ..................................... 1. A. horaimontana
    3. Heads many, in corymbs; leaves linear or narrowly oblong .............................. 2. A. morrisonicola