Madia gracilis |
Asteraceae tribe Heliantheae |
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common tarweed, grassy tarweed, gumweed, slender tarweed |
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Habit | Plants 10–200+ cm, odor resinous; self-compatible. | |
Stems | proximally pilose to hirsute, distally glandular-pubescent; glands yellowish, purple, or black; lateral branches seldom surpassing main stems. |
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Leaves | linear to oblong, 1–10(15) cm × 1–8(10) mm. |
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Inflorescences | open; panicle- or raceme-like arrays, rarely heads congested. |
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Involucres | depressed-globose to urceolate, 5–10 mm. |
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Ray florets | 3–10; corollas lemon-yellow or greenish yellow; rays 1.5–8 mm. |
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Disc florets | 2–16+; bisexual, fertile; corollas 2.5–5 mm, pubescent; anthers ± dark purple; ovaries developing; walls becoming dark; rigid. |
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Phyllaries | sometimes hirsute, finely or coarsely glandular-pubescent; glands yellowish, purple, or black; tips erect or somewhat reflexed; flat. |
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Heads | not showy. |
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Paleae | connate ? ½ their lengths. |
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Ray fruits | compressed; black, purple, or mottled; dull; |
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± | not beaked. |
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Disc fruits | similar to ray fruits. |
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2n | =32, 48. |
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Madia gracilis |
Asteraceae tribe Heliantheae |
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Distribution | ||
Discussion | Open or partially shaded slopes or flats in grasslands, meadows, shrublands, forests, disturbed areas, streambanks. Flowering May–Aug. 0–2100 m. All ecoregions. CA, ID, NV, WA; north to British Columbia, northeast to MT, southeast to UT, south to Mexico. Native. Madia gracilis often co-occurs with M. sativa. The two species are easily confused because of morphological similarities and inherent variation within both, especially when presented with only ill-prepared or incomplete herbarium material. Despite the tendency of M. gracilis to flower earlier than M. sativa, the two species are partially interfertile (Clausen 1951); hybridization may explain the difficulty of identifying some individuals. |
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Source | Flora of Oregon, volume 2, page 307 Bruce Baldwin, Gerald Carr |
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Sibling taxa | ||
Synonyms | Madia gracilis ssp. gracilis | |
Web links |
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