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Key to Asteraceae, Key C: herbaceous composites with opposite leaves and radiate heads
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https://fsus.ncbg.unc.edu/main.php?pg=show-key.php&keyid=40516
1 Ray florets white, pink, or purple (rarely pale yellow or lavender). | |
2 Ray floret (the lamina) articulate from the achene and falling, thus the mature heads not appearing papery. | |
5 Rays white or whitish-yellow; the laminae shorter, typically < 5 mm long (occasionally longer in Polymnia). | |
7 Stems not copiously glandular-pubescent; leaf blades lanceolate to broadly ovate or deltate, or pinnately to palmately lobed (Tridax); plants erect or ascending to procumbent (Tridax]; [non-natives of disturbed habitats, widespread; subtribe Galinsoginae]. | |
4 Heads with an involucre subtended by a calyculus of bracts (these often but not always reflexed); the phyllaries often appearing somewhat translucent or of a distinctly different color, shape, or texture from the leafy colored bracts below; [tribe Heliantheae; subtribe Coreopsidinae]. | |
9 Phyllaries connate for at least ¼ their length; heads with or without ray florets; [MS westwards in our area] | |
13 Leaves and phyllaries with large, scattered, embedded oil glands, making the plants strongly aromatic (the glands translucent in living plants, usually golden-brown or blackish in herbarium specimens); plants annual, decumbent and much branched from the base (except Tagetes, annual and generally erect and sparingly branched); [tribe Heliantheae; subtribe Pectidinae]. | |
14 Leaves pinnately lobed or pinnatisect (pinnately divided nearly to the midrib but the leaflets not separate), the margins of terminal segments usually serrate (sometimes entire). | |
17 Phyllaries distinct to their bases, or nearly so; ray florets 5-8; heads borne singly or in pairs/triplets; leaf surfaces puberulent | |
13 Leaves and phyllaries lacking embedded oil glands, though smaller punctate glands sometimes present; perennial or annual plants, upright and little or moderately branched below the inflorescence. | |
19 Leaves mainly cauline, the blades primarily linear, lanceolate oblanceolate, or occasionally oblong (if ovate, then leaves mostly cauline), the surfaces glabrous to strigose but not stipitate-glandular | |
20 Pappus absent, of scales, or coroniform (if coroniform then with 6-8 barbellulate bristles as in Jamesianthus); leaf blades unlobed; collectively widespread, including c. TX] | |
21 Heads smaller and many (10-300+), arranged into dense, flat-topped corymbs; disc florets 1-15; ray florets 0-2, the laminae inconspicuous; phyllaries 6 (-9), in 1 series; [collectively more widespread but absent from n. AL and wc. GA] | |
21 Heads larger and fewer (< 9 per inflorescence), arranged singly or in loose corymbs; ray florets 6-14, the laminae conspicuous; phyllaries 12-18, broadly ovate, squarrose and in several imbricate series; [on calcareous substrates in n. AL and wc. GA] | |
23 Inner phyllaries prickly with straight or uncinate prickles, and each enveloping a cypsela and swelling into a bur-like structure | |
23 Inner phyllaries unarmed, not becoming bur-like (though those of Melampodium do invest the fruit). | |
24 Plants with tack-glands or pit-glands on stems, leaves, and/or phyllaries; [waif, e. TX; native further westward] | |
24 Plants without tack-glands or pit glands. | |
25 Outer phyllaries orbicular to lance-linear, not connate; [native, collectively widespread in our area]. | |
27 Plants perennial, often trailing; pappus persistent, forming a minute, half-cup-shaped crown; [e. LA eastward, e. of MS river] | |
26 Taller, robust plants, the stems usually 5-40 cm long at maturity, erect; pappus absent or of 2 awns. | |
33 Plants with tack-glands or pit-glands on stems, leaves, and/or phyllaries; [waif, VA and NC northward; subtribe Madiinae] | |
33 Plants without tack-glands or pit-glands on stems, leaves, and/or phyllaries; [natives and non-natives, collectively widespread] | |
34 Paleae not notably clasping the cypsela; cypselae notably flattened (or weakly compressed/angled in Guizotia); heads small, the receptacle 3-8 mm in diameter (ca. 10-15 mm in Guizotia). | |
36 Cypselae of the rays and discs similar, monomorphic and not as above (the achenes weakly dimorphic in C. vialis, but the apical awns of similar length and the margins with only small, inconspicuous winglike projections) | |
37 Phyllaries apparently 4, the outer 4 foliaceous and forming a fused quadrangle which conceals the much smaller and narrower inner phyllaries (each inner phyllary subtending a ray floret); cypselae finely 32-40 ribbed | |
37 Phyllaries not as above, instead 5 or more and not forming a conspicuously fused quandrangle; cypselae angled or smooth (sometimes angled, but lacking many fine ribs) | |
47 Leaves linear, lanceolate, or ovate, almost always some leaves on a plant > 7 mm wide; plants from crowns, some species with thickened vertical storage roots (only H. tuberosus producing horizontal tubers); [collectively widespread in our area] | |
47 Leaves linear, 0.5-7 mm wide; plants from slender horizontal tubers; [c. FL north to s. AL] |