Herbs perennial, rarely annual, glabrous or pubescent, often farinose. Leaves simple, forming a rosette. Flowers usually heterostylous with pin (with longer styles) and thrum (with shorter styles) flowers; sometimes homostylous, in umbellate, racemose, subcapitate, or spicate inflorescences on scapes, with bracts; rarely solitary, scapes undeveloped. Calyx campanulate or cylindric, sometimes leaflike, 5-toothed. Corolla tube cylindric, not constricted at throat; limb 5-lobed, spreading or campanulate; lobes 2-cleft, margin entire. Stamens inserted on corolla tube; filaments very short; anthers obtuse. Ovary superior. Capsule globose, ovoid, or cylindric, dehiscing by valves, rarely with an operculum or crumbling; seeds numerous.
Approximately 500 species, mostly indigenous to the N temperate zone, with only a few outliers on the mountainous regions of Africa (Ethiopia), tropical Asia (Java and Sumatra), and
South America. About 300 species are native to China.
Many species are imperfectly known, sometimes collected only once. This is reflected occasionally by missing details on pin or thrum morphology, fruiting characteristics, or ecology.
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The 300 species are represented by 24 sections according to C. M. Hu:
1. Sect. Monocarpicae Franchet ex Pax: spp. 1--13.
2. Sect. Obconicolisteri I. B. Balfour: spp. 14--23.
3. Sect. Cortusoides I. B. Balfour: spp. 24--40.
4. Sect. Malvacea I. B. Balfour: spp. 41--47.
5. Sect. Auganthus (Link) Pax ex I. B. Balfour: spp. 48--50.
6. Sect. Pycnoloba I. B. Balfour: sp. 51.
7. Sect. Ranunculoides Chen & C. M. Hu: spp. 52--53.
8. Sect. Primula: sp. 54.
9. Sect. Carolinella (Hemsley) Pax: spp. 55--62.
10. Sect. Bullatae Pax: spp. 63--66.
11. Sect. Petiolares Pax: spp. 67--115.
12. Sect. Proliferae Pax: spp. 116--134.
13. Sect. Amethystina I. B. Balfour: spp. 135--142.
14. Sect. Sikkimensis I. B. Balfour: spp. 143--150.
15. Sect. Crystallophlomis Rupr.: spp. 151--191.
16. Sect. Cordifoliae Pax: spp. 192--196.
17. Sect. Aleuritia Duby: spp. 197--242.
Spp. 238--242 are recognized in Europe and North
America as Sect. Armerina.
18. Sect. Minutissimae Pax: spp. 243--259.
19. Sect. Souliei I. B. Balfour ex W. W. Smith & Forrest:
spp. 260--265.
20. Sect. Dryadifolia I. B. Balfour: spp. 266--268.
21. Sect. Denticulata Watt: spp. 269--274.
22. Sect. Capitatae Pax: spp. 275--276.
23. Sect. Muscarioides I. B. Balfour: spp. 277--289.
24. Sect. Soldanelloides Pax: spp. 290--300.
