This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Perennial woolly dioecious or polygamo-dioecious herbs, with alternate and basal leaves, and small discoid many-flowered heads usually capitate, glomerate or corymbose. Involucre oblong, ovoid or campanulate, its bracts scarious, imbricated in several series, the outer shorter, usually woolly. Receptacle convex, or nearly flat, foveolate, not chaffy. Staminate flowers with a truncate or minutely dentate corolla, usually undivided style and scanty pappus of club-shaped smooth or minutely barbed bristles. Pistillate or perfect flowers with tubular mostly 5-toothed corollas, 2-cleft style, and copious pappus of capillary naked bristles, slightly united at the base, the style often crimson. Achenes oblong, terete, or slightly compressed. [Latin, in allusion to the fancied resemblance of the sterile pappus to insect antennae.]
About 50 species, natives of the north temperate zone and southern South America. In addition to the following, many others occur in the western parts of North America. The patches of fertile and sterile plants are usually quite distinct, and the sterile plants of some species are much less abundant than the pistillate. Perfect achenes are, however, abundant, parthenogenesis being a known feature of this genus. Type species: Antennaria dioica (L.) Gaertn.
* Pappus-bristles of sterile flowers with club-shaped or dilated tips. † Plant not stoloniferous; basal leaves oblanceolate.
1. A. carpathica.
†† Plants stoloniferous, growing in patches. Involucral bracts of fertile heads dark brownish green, lanceolate, acute or acuminate; plant 1'-4' high.
2. A. alpina.
Basal leaves and those of the ends of stolons bright green and glabrous above from the first. Basal leaves small, spatulate, with only 1 prominent nerve.
3. A. canadensis.
Basal leaves large, obovate, distinctly 3-nerved.
4. A. Parlinii.
Basal leaves and those of the ends of stolons dull green, arachnoid at first, becoming glabrous.
Basal leaves large, mostly 2'-5' long, mostly 10" wide or wider, oblong to obovate, 3-5-nerved.
Stolons leafy only at the ends, scaly-bracted: head solitary.
5. A. solitaria.
Stolons leafy throughout; heads corymbose or subcapitate.
6. A. plantaginifoha.
Basal leaves smail, 2 long or less, spatulate to oblanceolate or obovate, mostly 1-nerved. Basal leaves persistently appressed silvery-silky on both sides.
7. A. microphylla.
Basal leaves dull, the upper surface more or less persistently arachnoid. Basal leaves abruptly apiculate; stolons leafy throughout.
8. A. neodtoica.
Basal leaves obtuse or acute.
Stolons leafy throughout; western species. Basal leaves spatulate.
9. A. aprica.
Basai leaves obovate.
10. A. campestris.
Stolons leafy only at the ends.
11. A. neglecta.
** Pappus-bristles of sterile flowers not dilated, barbellate; plant about 1' high, tufted; head solitary.
12. A. dimorpha.