|Streptocarpus subsp. var.||Cape primrose|
Streptocarpus is a genus of herbaceous flowering plants in the family Gesneriaceae, closely related to the genus Saintpaulia. One common name is Cape Primrose, referring to the nativity of several species to South Africa and their superficial resemblance to the genus Primula. The genus is native to parts of Africa and Madagascar (with a few odd species in Asia that probably do not belong in the genus). The plants often grow on shaded rocky hillsides or cliffs. About 155 species of Streptocarpus are currently recognized, the first described being S. rexii. They are found growing on the ground, rock crevices, and almost anywhere the seed can germinate and grow. Some species such as S. dunnii are unifoliate with the plant producing no true leaves, only a single cotyledon that continues to grow throughout the life of the plant. The unifoliate species are monocarpic and die after producing seeds. Other species are perennial and come into flower during different parts of the year. Members of subgenus Streptocarpella are more typical caulescent herbs and are sometimes grown as bedding or hanging plants. The genus is defined by having a spirally twisted fruit (hence the name "streptocarpus"), although this character is also found in some other Old World genera of Gesneriaceae. Recent phylogenetic studies strongly suggest that although it does not have a twisted fruit the genus Saintpaulia has evolved from within subgenus Streptocarpella.
The leaves of some perennial (and particularly unifoliate) Streptocarpus are unusual because as winter approaches they slowly die back to an abscission line midway down the leaf. The tip of the leaf will gradually die back to this line. In most flowering plants an absiscion line forms at the base of the leaf.
A complete list of the species and their synonyms can be found at the Smithsonian Institution's World Checklist of Gesneriaceae.
The name Streptocarpus means twisted fruit.
A large number of hybrids and cultivars have been produced; S. rexii entered into many of the early hybrids but more recent cultivars often involve many different species. Recent cultivars have been bred to remain in bloom throughout the year. Over the past few years work has been done through hybridizing to bring other traits such as red flowers into modern hybrids. There are thousands of cultivars that are now grown as both houseplants and in the garden. The colors of the flowers range anywhere from red, white, yellow, blue, and everything in between including nearly black, except for a deep orange. Many flowers have markings in the "throat". More recently, breeders have been working to introduce floral fragrance to new hybrids from the relatively few species that have this trait.
|Standard Cyclopedia of Horticulture|
Streptocarpus (Greek compound, meaning twisted fruit). Gesneriaceae. Cape Primrose. Herbs, frequently villous or lanate, adapted to greenhouse culture; choice plants, grown for the showy bloom.
Stemless, with 1 or more spreading radical lvs. or rarely with a st. and opposite lvs.: peduncles scape-like or axillary, sometimes 1-2-fld., sometimes cymose, several-fld.: fls. pale purple or blue, showy; calyx 5-parted; corolla-tube elongated, cylindrical or spreading above, limb obliquely 2-lipped, posterior lip 2-cleft, anterior larger, 3-cleft; perfect stamens 2; disk short-annular; ovary superior, imperfectly 4-celled: caps. linear, terete, splitting in 2, rarely 4 valves.—About 60 species, natives of S. Afr. and Madagascar. In Oct., 1826, there bloomed at Kew a most interesting gloxinia-like little plant, seeds and specimens of which had been collected in S. Afr. by Bowie, on the estate of George Rex, at Knysna. The plant was described as Didymocarpus Rexii. It is a stemless plant, with 1 or rarely 2 long-tubular nodding pale blue fls. on each of several short scapes, and with several clustered root-lvs. It proved to be a profuse bloomer and easy to grow. "So abundantly does it produce seed," wrote W. J. Hooker, in 1830, "that new individuals come up as weeds in the neighboring pots, and a succession of flowers may be obtained at almost every period of the year." In 1828, John Lindley made the genus Streptocarpus for this plant, calling it S. Rexii, the name it now bears. It appears to have been nearly thirty years after the intro. of S. Rexii that another streptocarpus bloomed in England. This second species was S. polyanthus, which may be taken as the type of a group that has one leaf lying on the ground and from the midrib of which arise successive several-fld. scapes. The intro. of this curious plant seems to have revived the interest in streptocarpuses, an interest that has been kept alive by the frequent intro. of other species. The chief stimulus to the systematic breeding of these plants seems to have been the intro. of S. Dunnii, said by J. D. Hooker to be "quite the monarch of its beautiful genus" (but now excelled by S. Wendlandii). Seeds of this species were sent to Kew in 1884 by E. G. Dunn, of Cape Town. It is one of the monophyllous section to which S. polyanthus belongs. In the meantime, S. parviflorus, a species allied to S. Rexii, had been intro. from the Cape region. With the three species, S. Rexii, S. parviflorus, and S. Dunnii, Wm. Watson of the Royal Gardens, Kew, set to work systematically to breed a new race of streptocarpus, and his efforts met with unqualified success. When the hybrids came to notice in 1887, the Gardener's Chronicle made the following comment on the value of the work: "The results are very striking, and we can hardly doubt that Mr. Watson has set the foundation of a new race of plants, parallel in importance to the Achimenes and Tydaeas." Several hybrid races have now been produced and several interesting species have been intro. from the wild, so that Streptocarpus seems to be destined to become a very important and popular garden genus.
Bentham and Hooker's treatment divides the Gesneriaceae into two great tribes: Gesnereae, with ovary more or less inferior and fruit a capsule; Cyrtandreae, with ovary superior and fruit sometimes a berry. The latter tribe, the species of which have been monographed by C. B. Clarke in vol. V of DeCandolle's "Monographiae Phanerogamarum," contains the genera Streptocarpus, Episcea, Cyrtandra, Aeschynanthus, Ramondia, and others. Streptocarpuses are of three groups: the stemless monophyllous species, with one prostrate leaf from the midrib of which the scapes arise (this leaf is really an enlarged cotyledon, the other cotyledon not enlarging); the stemless species, with several or many radical more or less primula-like leaves (whence the English name "Cape primrose"); the stem-bearing species, with opposite cauline leaves. The cultivated species chiefly represent the first two sections. In the American trade, four specific names chiefly occur, S. Rexii, S. Galpinii, S. Dunnii, and S. Wendlandii; but since the hybrids represent several other species, these additional species are inserted in the following account. Streptocarpus is an African genus. The stem-bearing section is confined to central Africa and Madagascar, and the others to South Africa. Clarke's monograph, 1883, describes nineteen species, but S. Dunnii, S. Wendlandii, S. Galpinii, and many others have since been discovered.
Streptocarpuses are not difficult plants to grow. They are usually raised from seeds, the seedlings blooming in eight to fifteen months from starting. The seeds are very small, and care must be taken not to cover them too deep. Give an open sunny place in an intermediate temperature. They are not stove or warmhouse plants. Of the new hybrid forms, seeds sown in February or March should produce plants that will bloom the following fall and winter; after blooming, the plants may be discarded, for better results are usually secured from new plants than from those more than one season old. The season of most profuse bloom is summer, but the bloom continues until winter. The monophyllous species can be propagated also by cuttings of the leaf. Some fanciers of Cape primroses advise propagating select types by leaf-cuttings or by division. CH
Streptocarpus require bright indirect light and can be grown near a window or under fluorescent lighting. Streptocarpus are propagated by seeds, divisions, and leaf cuttings. The tiny seeds are dust-like and should be sown on the surface of the growing medium; they require light to germinate. The leaves can be cut into sections or down the middle to remove the central vein and then planted horizontally in light potting soil containing vermiculite and perlite. Members of subgenus Streptocarpella are easily propagated from stem cuttings.
Streptocarpus flowers are born on short and long peduncles (flower stems) that attach to the leaf stem. Several peduncles may be produced per leaf. New flowers come with new leaf growth.
Rosulate Streptocarpus form small clumps. As the plant grows it produces creeping stems that produce roots and will eventually separate to form other colonies. These creeping stems are called rhizomes.
Pests and diseases
- Selected species
- Streptocarpus baudertii
- Streptocarpus candidus
- Streptocarpus caulescens
- Streptocarpus cyaneus
- Streptocarpus dunnii
- Streptocarpus formosus
- Streptocarpus glandulosissimus
- Streptocarpus grandis
- Streptocarpus Hybrid Cultivars
- Streptocarpus johannis
- Streptocarpus kirkii
- Streptocarpus pentherianus
- Streptocarpus polyanthus
- Streptocarpus primulifolius
- Streptocarpus rexii
- Streptocarpus saxorum
- Streptocarpus wendlandii
The following species are either little known or have not found their way into general cult.: CH
- S. armitagei, Baker & Moore, is closely allied to S. Dunnii, differing in having a corolla much less funnel-shaped and straighter, with less spreading lobes; originally described as solitary-lvd., but 4 lvs. are said to have developed in the cult. plant. S. Afr.CH
- S. banksii, Lynch (S. Wendlandii x some hybrid), has 2 lvs. about 19x13 in. for the lower, the second somewhat smaller: fls. large, purple-blue. Garden hybrid.CH
- S. biflorus, Pucci, is a name appearing in horticultural journals for some unknown plant, which is said to have several blue fls.CH
- S. bifloro-polyanthus, Duch., is a hybrid, the female parent of which is S. polyanthus, the male the above-mentioned S. biflorus: it is said to have 5 ovate-oblong, crenate, rugose lvs.; several scapes with 2-4 pale lilac fls. F.S. 23:2429.CH
- S. blythinii, Lynch (S. Wendlandii X S. cyaneus), has 2-5 lvs., the largest of which is 15x9 in. and another is 12 x 7 in., green beneath, in some cases reddish toward the tip, in others with the color here and there: scapes 9-10, each with 5-14 fls., about 14 in. high: fls. about 1 1/2 in. across, lavender or bluish purple; petals marked with dark purple stripes. Garden hybrid. CH
- S. cantabrigiensis, Lynch (S. cyaneus X S. Dunnii), has several lvs. which are 7-8 x 3 in.: scapes about 7 in. high, 2-12-fld., conspicuously hairy: calyx-segms. linear-lanceolate; corolla 2 in. long, about 1 3/8 in. across, tube funnel-shaped, lobes rounded, throat white with 7 deeply colored lines, limb deep rose. Garden hybrid. G.C. III.59:131.CH
- S. Gaudinii, Hort., is offered in the trade.—S. Greenii, Hort. ex Wilson (S. Saundersii x S. Rexii), is dwarfer and more compact than the former parent, the scapes many-fld: fls. pale lilac-blue. Garden hybrid. G.C. II. 17:303. Said to be the first hybrid streptocarpus.CH
- S. holstii, Engl., resembles S. caulescent; plant about 1 1/2 ft. high, producing a large number of sts., each bearing 6-8 dark violet-blue fls. 3/4-1 in. long, spotted with white on the midlobe of the lower lip. German E. Afr. (Section I.) B.M. 8150.CH
- S. hybridus. Hort., is a name applied to garden hybrids in general.—S. Kirkii, Hook. f. Caulescent; st. 4-6 in. high, stout, erect, hairy: lvs. 1-2 in. long, broadly ovate, obtuse, crenate, finely pubescent on both surfaces, base rounded or cordate; petiole 1/3-1/2 in. long: scapes axillary, very slender, 3-4 in. high: fls. drooping, opposite; calyx-lobes lanceolate, pubescent; corolla 3/4 in. long, pale lilac, tube hairy, upcurved, broad and subcampanulate, mouth expanded, lobes short rounded, ciliate, Trop. E. Afr. B.M. 6782. (Section I.) Allied to S. caulescens.CH
- S. lichtensteinensis, Hort. (S. Wendlandii X S. Watsonii), has 2 lvs., 1 prostrate and the other smaller and erect: fls. numerous, lilac-blue. Garden hybrid.CH
- S. mahonii, Hook. f. Acaulescent: lf. solitary, 1 ft. or more long, flat on the ground, sessile, ovate-oblong, crenulate, tip rounded, base cordate: scapes many, crowded, densely pilose: fls. long-pedicelled; calyx-segms. pubescent, linear, corolla violet, tube 2/3 in. long, pubescent, decurved, somewhat inflated above; lobes rotundate. Brit. Cent. Afr. B.M. 7857.CH
- S. multiflora, Laing., is a seedling of S. Rexii, with up to 30 large bluish purple fls., which have darker purple lines in the throat and running up onto the lower lip. Garden hybrid. G.C. III. 18:211; 32:327. I.H. 43. p. 67.CH
- S. orientalis, Craib. Caulescent; st. solitary, erect, simple, 6-16 in. high, leafy: lvs. ovate to elliptic-ovate, apex obtuse, base cuneate, crenate or crenate-serrate, 1 – 3 1/2 x 3/4 – 2 3/4 in., both surfaces glandular-pilose; petioles up to 2 in. long: infl. axillary, cymose: calyx-lobes lanceolate or linear-lanceolate, white-glandular-hairy outside; corolla purple outside, paler within, tube over 1 in. long, limb about 3/4 in. across, lobes reflexed-spreading, wide oblong, tip rounded. Siam. CH
- S. veitchii, Hort, is offered in the trade.CH