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Aquatic and Wetland Vascular Plants of the Northern Great Plains

Aster L. -- Aster

Annual or most often perennial herbs with simple, alternate leaves. Heads radiate (discoid in A. brachyactis), (1) few to many, often showy, borne at the ends of leafy stems or branchlets, often aggregated in paniclelike inflorescences; ray florets pistillate, the ligules white to pink to various shades of blue or purple, mostly more than 0.5 mm wide; when rays are absent, the outermost florets on the disk pistillate with a slender, tubular corolla; involucral bracts in 2 or more series, usually imbricate, herbaceous and green-tipped, chartaceous at the base; receptacle naked, flat or slightly convex; disk florets perfect, the corollas yellow, white or red to purple; style branches flattened with minutely hairy appendages. Achenes mostly several-nerved, rarely 2-nerved; pappus of numerous capillary bristles.

Lead Characteristic Go To
1 Rays lacking; plants annual, taprooted. A. brachyactis
1 Rays evident; plants perennial. Lead 2
2 Involucres, peduncles and upper stem glandular-pubescent. Lead 3
2 Involucres, peduncles and upper stem glabrous or pubescent but not glandular. Lead 4
3 Leaves lanceolate, clasping the stem. A. novae-angliae
3 Leaves linear to linear-oblanceolate, not clasping. A. pauciflorus
4 Pappus a double row of capillary bristles, the outer row much shorter than the inner; heads clustered in a terminal, somewhat flat-topped inflorescence; rays white. A. pubentior
4 Pappus a single row of equal capillary bristles; heads usually in paniclelike inflorescences; rays white to pink or blue. Lead 5
5 Leaves auriculate-clasping. Lead 6
5 Leaves sessile but not auriculate-clasping, only weakly clasping if at all. Lead 7
6 Plants arising from a short rhizome or caudex; leaves of the inflorescence not conspicuously crowded. A. puniceus
6 Plants arising from long creeping rhizomes; leaves of the inflorescence not conspicuously crowded. A. lucidulus
7 Leaves linear, 2-6 mm wide; rhizome slender, 0.5-1.5(2) mm thick; heads rather few (sometimes solitary) and uncrowded. A. junciformis
7 Leaves linear to linear-lanceolate, 3-25 mm wide; rhizome stouter, mostly 2-6 mm thick; heads usually many, often crowded. Lead 8
8 Veinlets of the leaf forming a conspicuous reticulum on the underside, outlining nearly equal-sided areolae. A. praealtus
8 Veinlets of the leaf forming a rather inconspicuous reticulum on the underside, the areolae, if evident, clearly longer than broad. Lead 9
9 Involucral bracts mostly not strongly imbricate in flowering heads, the outer bracts usually at least 2/3 as long as the inner ones in mature heads; lobes of the disk corollas comprising 19-36% of the limb (the widening portion of the tubular corolla). A. hesperius
9 Involucral bracts more or less strongly imbricate in flowering heads, the outer bracts seldom as much as 2/3 as long as the inner ones in mature heads; lobes of the disk corollas 30-45% of the limb. A. simplex

49. Asteraceae, the Aster Family
2. Aster L. -- Aster
1. Aster brachyactis Blake -- Rayless aster
2. Aster hesperius A. Gray -- Marsh aster
3. Aster junciformis Rydb. -- Rush aster
4. Aster lucidulus (A. Gray) Wieg.
5. Aster novae-angliae L. -- New England aster
6. Aster pauciflorus Nutt. -- Few-flowered aster
7. Aster praealtus Poir. -- Willowleaf aster
8. Aster pubentior Cronq.
9. Aster puniceus L. -- Swamp aster
10. Aster simplex Willd. -- Panicled aster

Return to Family -- Asteraceae - The Aster Family
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