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Oenothera L.
待宵草(月見草)屬
HOCH, PETER C. and WAGNER, WARREN L.
Annual, biennial or perennial herbs, from a taproot or clumped and spreading by rhizomes or lateral roots. Leaves alternate, often in a basal rosette, entire, toothed, or pinnately lobed; stipules absent. Flowers actinomorphic, 4-merous, in axils of upper reduced leaves, usually opening near sunset; sepals 4, reflexed in flower; petals 4, yellow, white or rose-purple, tip often notched; stamens 8; pollen shed singly; ovary 4-locular; stigma deeply 4-lobed. Fruit a many-seeded capsule, usually dehiscent, straight or curved, terete to 4-ribbed or winged, +/- sessile. Seeds in 2 (1 or 3, not in Taiwan) rows per locule or clustered.
A genus of about 120 species native to temperate or subtropical N and S America but some species widely naturalized; five species occur in Taiwan. Several species in Taiwan have the feature of permanent translocation heterozygosity, characterized by self-pollination, about 50% pollen fertility (note: sterile pollen is smaller than fertile and thus can be assessed with a hand lens), and the formation of a ring of 14 chromosomes at meiotic metaphase I.
- Dietrich, W. & W.L. Wagner. 1988. Systematics of Oenothera section Oenothera subsection Raimannia and subsection Nutantigemma (Onagraceae). Syst. Bot. Monogr. 24: 1-91.
- Munz, P.A. 1965. Onagraceae. N. Amer. Fl. II, 5: 1-278.
- Peng, C. I & S. Huang. 1986. Oenothera laciniata Hill (Onagraceae), a previously unrecorded species in Taiwan. Bot. Bull. Acad. Sin. 27: 45-51.
KEY TO SPECIES
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1 |
Petals white, fading purple; seeds in clusters in each locule;fruit club-shaped, 4-winged. |
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Oenothera tetraptera |
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Petals yellow, fading pale yellow to orange or red; seeds in 2 rows in each locule; fruit lanceolate or cylindrical, sometimes slightly wider toward apex, not winged. |
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(2) |
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2 (1) |
Fruit lanceolate; erect biennial; flowers numerous in generally dense spikes; seeds angled, irregularly pitted. |
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(3) |
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Fruit cylindrical; usually decumbent or weakly erect annual or perennial (O. stricta sometimes a biennial); flowers few in upper axils; seeds ellipsoidal, not angled. |
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(4) |
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3 (2) |
Leaves distinctly crinkled, at least toward the base; seeds c. 50% abortive; sepals usually reddish, 28-45 mm long; petals 35-50 mm long; anthers 10-12 mm long. |
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Oenothera glazioviana |
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Leaves flat, not crinkled; seeds c. 100% fertile; sepals green, rarely reddish, 12-20(-28) mm long; petals 10-25 (-30) mm long; anthers 3-6(-9) mm long. |
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Oenothera biennis |
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4 (2) |
Fruit wider toward apex; floral tube straight in young buds; petals 15-25(-30) mm long, generally with a red spot at base; sepals 14-20 mm long. |
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Oenothera stricta |
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Fruit the same diameter throughout or tapering toward apex; floral tube curved upward in young buds; petals 5-13(-20) mm long, without a red spot at base; sepals 5-15 mm long. |
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Oenothera laciniata |
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Lower Taxa
Related Synonym(s):
Related Links (opens in a new window) |
Treatments in Other Floras @ www.efloras.org
Other Databases
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