Perennials or subshrubs. Stems usually twining-climbing, sometimes ascending, decumbent, erect, procumbent, prostrate, or trailing, rarely almost absent, usually hairy, hairs not branched, glandular, or stellate, sometimes glabrate, glabrescent, or glabrous. Leaves petiolate; blade usually cordate, elliptic, linear, oblong, oblong-hastate, orbiculate, oval, ovate, reniform, tri­angular, or triangular-hastate, rarely palmately 7–9-lobed, (15–)20–130 mm, base usually lobed or truncate, sometimes cuneate, surfaces glabrate, glabrescent, glabrous, ± pilose, tomentose, tomentulose, or villous. Inflorescences usually axillary, rarely terminal, compound cymes, bracteate; peduncles 1(–4)-flowered. Flowers: sepals ± elliptic, lanceolate, lance-ovate, oblong, oblong-ovate, oval, or ovate, (5–)8–15(–25) mm; corolla usually white, sometimes cream, pink, purple, red, or yellow, campanulate to funnelform, (20–)25–60(–73)[–88] mm, limb entire or 5-lobed or -angled, rarely multilobed; ovary 1-locular, sometimes with partial septum; styles 1; stigma lobes 2, linear to oblong, apices blunt. Fruits capsular, ± globose, dehiscence irregular. Seeds (1–)2–4, pyramidal to subglobose or trigonous, glabrous, papillate, smooth, or reticulate. x = 12.

Distribution

North America, Mexico, South America, Eurasia, Africa, Atlantic Islands, Pacific Islands, Australia.

Discussion

Species ca. 30 (20 in the flora).

H. Hallier (1893) and W. H. Lewis and R. L. Oliver (1965) summarized arguments for treat­ing Calystegia and Convolvulus as distinct genera. In a molecular analysis, M. A. Carine et al. (2004) found Calystegia nested within Convolvulus.

Species delimitation is problematic throughout Calystegia, with geographic and morphological intergradation between taxa, and often arbitrary limits have to be adopted to avoid impractically broad species. Hybridization is common where species overlap geographically. It is difficult to pinpoint any species which is not taxonomically subdivided and which does not intergrade or hybridize with others.

Selected References

None.

Lower Taxa

Calystegia atriplicifolia, Calystegia catesbeiana, Calystegia collina, Calystegia felix, Calystegia hederacea, Calystegia longipes, Calystegia macounii, Calystegia macrostegia, Calystegia malacophylla, Calystegia occidentalis, Calystegia peirsonii, Calystegia pubescens, Calystegia purpurata, Calystegia sepium, Calystegia silvatica, Calystegia soldanella, Calystegia spithamaea, Calystegia stebbinsii, Calystegia subacaulis, Calystegia vanzuukiae

Key

1	Bracts (1–)2–10(–50) mm distant from sepals, margins entire, lobed, or toothed.	> 2
2	Stems erect, sometimes intertwined; leaf blades usually linear to narrowly triangular, sometimes ovate, base not lobed or hastate-lobed and lobes ± linear, oblong, or trian­gular, 1-pointed.	Calystegia longipes
2	Stems ascending, decumbent, procumbent, trailing, or twining-climbing; leaf blades oblong, oblong-ovate, orbiculate, ovate, broadly to narrowly triangular, triangular-hastate, or palmately 7–9-lobed, base usually lobed and lobes rounded or 1–3-pointed, base rarely cuneate or ± truncate.	> 3
3	Leaf blades oblong, oblong-ovate, orbiculate, or ovate, base lobed and lobes rounded or base cuneate to ± truncate.	Calystegia felix
3	Leaf blades usually broadly to narrowly triangular, ovate-triangular, or triangular-hastate (daggerlike), or palmately 7–9-lobed, sometimes ± reniform, base usually lobed and lobes rounded or 1–3-pointed, base rarely cuneate or ± truncate.	> 4
4	Herbage glabrous.	> 5
5	Leaf blades ± triangular to ovate-triangular; bracts linear, margins entire or proximally lobed or toothed.	Calystegia purpurata
5	Leaf blades narrowly triangular-hastate; bracts elliptic to broadly elliptic-oblong, margins entire.	Calystegia peirsonii
4	Herbage usually hairy, at least near leaf blade sinus and/or tip of peduncle, sometimes glabrate or glabrescent.	> 6
6	Leaf blades palmately 7–9-lobed.	Calystegia stebbinsii
6	Leaf blades not palmately lobed.	> 7
7	Bract margins entire.	> 8
8	Leaf blades ± triangular-hastate, middle lobe ± lance-linear; bracts 1–2 mm distant from sepals, linear, 5–16(–20) × 0.5–1.5 mm.	Calystegia vanzuukiae
8	Leaf blades ± triangular; bracts (1–)3–7 mm distant from sepals, linear to linear-oblong, 4–13(–18) × 1–4(–5) mm.	Calystegia occidentalis
7	Bract margins proximally lobed or toothed.	> 9
9	Herbage tomentose to villous; leaf blades ± broadly to narrowly triangular, basal lobes 2(–3)-pointed.	Calystegia malacophylla
9	Herbage glabrate or hairy; leaf blades narrowly triangular or triangular-hastate, basal lobes rounded or 1–2-pointed.	> 10
10	Bracts 1–2 mm distant from sepals, linear, 5–16(–20) × 0.5–1.5 mm.	Calystegia vanzuukiae
10	Bracts 2–12(–15) mm distant from sepals, lanceolate, linear, linear-oblong, oblanceolate, or narrowly to broadly triangular, 5–22(–30) × 2–4(–7) mm.	Calystegia occidentalis
1	Bracts immediately subtending, less than 1 mm from, sepals, margins entire.	> 11
11	Corollas horticultural doubles, limbs multilobed; stamens and ovaries absent.	Calystegia pubescens
11	Corollas not doubles, limbs weakly 5-lobed, 5-angled, or entire; stamens and ovaries present.	> 12
12	Bracts 1.5–3.5(–4) mm wide.	> 13
13	Herbage tomentellous, tomentose, or villous.	Calystegia collina
13	Herbage glabrous or ± hairy, not tomentellous, tomentose, or villous.	> 14
14	Leaf blades narrowly triangular-hastate, base lobed, lobes ± oblong to rhombic, 1-pointed.	Calystegia peirsonii
14	Leaf blades rounded-deltate to triangular-hastate, base cuneate or lobed, lobes not oblong to rhombic and 1-pointed.	> 15
15	Herbage glabrous; bract apices acute to obtuse.	Calystegia atriplicifolia
15	Herbage sparsely hairy; bract apices acute.	Calystegia subacaulis
12	Bracts 4–30 mm wide.	> 16
16	Perennials or subshrubs, rootstock woody.	Calystegia macrostegia
16	Perennials, rhizomatous.	> 17
17	Leaf blades ± reniform, ± fleshy; corollas pink.	Calystegia soldanella
17	Leaf blades not reniform, not fleshy; corollas usually pink, cream, or white, rarely purple.	> 18
18	Stems usually erect, procumbent, or twining-climbing, sometimes trailing or proximally erect and distally twining-climbing; mostly c, e North America.	> 19
19	Leaf blades triangular to triangular-hastate, base lobed, lobes 2(–3)-pointed; corollas usually pink, sometimes purple or white, 21–32(–35) mm.	Calystegia hederacea
19	Leaf blades ± cordate, elliptic, elliptic-ovate, linear, oblong, ovate, broadly to narrowly triangular, or triangular-hastate, base cuneate, rounded, or lobed, lobes obtuse, rounded, or 1–2-pointed; corollas pink or white, (20–)35–65(–70) mm.	> 20
20	Stems erect.	Calystegia spithamaea
20	Stems usually twining-climbing, sometimes trailing or proxi­mally erect and distally twining-climbing.	> 21
21	Leaf blades elliptic-ovate, basal lobes obtuse or rounded, surfaces some­times whitish tomentose.	Calystegia catesbeiana
21	Leaf blades ± cordate, linear, oblong, oblong-ovate, oval, ovate, triangular, or triangular-hastate, basal lobes usually 1–2-pointed, sometimes rounded or 1-pointed, surfaces not whitish.	> 22
22	Leaf blade basal sinuses usually acute to rounded, sometimes quadrate, rarely closed; bracts proximally flat or keeled, not or scarcely saccate, margins not or scarcely enfolding sepals, apices acute to subobtuse or truncate.	Calystegia sepium
22	Leaf blade basal sinuses ± quadrate to rounded; bracts proximally saccate, margins enfolding sepals, apices obtuse to truncate.	Calystegia silvatica
18	Stems usually ascending-decumbent, sometimes procumbent, suberect, trailing, or proximally erect and distally weakly twining-climbing, or almost absent; mostly w North America (C. macounii plains and west).	> 23
23	Herbage glabrous.	Calystegia atriplicifolia
23	Herbage moderately or sparsely hairy, puberulent, tomentellous, tomentose, or villous.	> 24
24	Herbage sparsely hairy, hairs appressed.	Calystegia subacaulis
24	Herbage moderately or sparsely hairy, puberulent, tomentellous, tomentose, or villous, hairs not appressed.	> 25
25	Leaf blade basal lobes ± rhombic, rounded; east of California.	Calystegia macounii
25	Leaf blade basal lobes 1–3-pointed; California.	> 26
26	Stems mostly to 60(–100) cm; leaves not in basal rosettes.	Calystegia malacophylla
26	Stems to (2–)50 cm or almost absent; leaves usually in basal rosettes.	> 27
27	Herbage tomentellous, tomentose, or villous; leaf blade margins ± undulate.	Calystegia collina
27	Herbage moderately to sparsely hairy; leaf blade margins not notably undulate.	Calystegia subacaulis