Crassulaceae J.St.-Hil.

Hind, D.J.N. (2009). Neotropical Crassulaceae.

Morphology

Description

Perennial herbs, rarely annual or biennial , rarely small shrubs, usually stem and/or leaf succulents. Leaves opposite or alternate , rarely verticillate , exstipulate , usually simple , usually glabrous , often glaucous , rarely with glands in leaf surface, sometimes pubescent , hairs either unicellular or multicellular and glandular - capitate or eglandular, margins usually entire , sometimes serrate , crenate or dentate , rarely coarsely lobed . Flowers usually in terminal cymose inflorescences, less often in spikes or racemes or solitary in leaf-axils, with or without bracts, regular, hermaphrodite , rarely unisexual and dioecious , mostly (3-)4-5 (-± 30)- merous ; sepals 4-5 (-6), free or united into tube, persistent ; petals same number as sepals, free or variously connate ; stamens hypogynous or epipetalous, as many as petals or twice as many, in one whorl (Crassula-lineage) or more usually two whorls (Sedum-lineage), frequently obdiplostemenous, with outer whorl alternate and free from petals and inner whorl adnate to petals; filaments free or adnate to petals; anthers dorsifixed, bithecous, introrse, opening by a longitudinal slit; nectaries scale-like and usually present between the stamens and carpels. Carpels superior , equal in number to petals, free or slightly connate at base, unilocular; ovules (few-) many, inserted on adaxial suture, submarginal or proximally axile ; styles short or elongated, stigmatic surface on inner side of apex . Fruit usually of separate follicles, rarely a capsule , follicles membranous or leathery, often surrounded by persistent membranous corolla , opening on adaxial side. Seed minute, glabrous , testa variously striate and sometimes ornamented with ridges or papillae; endosperm usually present and sparse; embryo straight.

Distribution

Distribution in the Neotropics

• Largest genus is Sedum L. with about 500 species in total.
• Echeveria DC. is the largest in the Western hemisphere with c. 150 species.
• Sedum follows Echeveria with c. 110 spp. in the Neotropics.
• Crassula L. has c. 11 spp. in the Neotropics.
• Villadia Rose contains c. 10 in Peru.

General Description

Number of genera

• There are four native genera (Sedum, Echeveria, Crassula and Villadia) and one cultivated (Kalanchoe).

General notes

• Main areas of speciation include Africa (dry areas), Madagascar, Macaronesia and Mexico.
• Up to six subfamilies are recognized but following DNA analysis only two main lineages are seen clearly - the Crassula-lineage and the Sedum-lineage.
• Mostly plants of dry, rocky habitats, usually terrestrial but rarely epiphytic and very rarely aquatic.

Diagnostic

Useful tips for generic identification

• Crassula spp. are usually prostrate or aquatic herbs, typically with isostemonous flowers.
• Echeveria spp. have obovatefleshy leaves, usually arranged in a rosette, and lateral racemose inflorescences
• Sedum spp. have paniculate cymes; both genera have free or basally connate petals.
• There are several species of Kalanchoe that are cultivated, some naturalized; they are best recognized by flowers with (4) fused petals forming a tube, and many species have lobed, crenate or serrate margined leaves. A number of species of Kalanchoe , formally in the genus Bryophyllum , have plantlets on the leaf margins.

Literature

Important literature

Bywater, M. & G. E .Wickens. (1984). New World species of the genus Crassula. Kew Bull. 39(4): 699-728.

Claussen, R. T. (1959). Sedum of North America north of the Mexican Plateau. An exposition of taxonomic methods. Comstock Publishing Associates, Ithaca, New York. pp. 380.

Freire Fierro, A. (2004). Crassulaceae. In: G. Harling & L. Andersson (eds), Flora of Ecuador 73: 3-16. Botanical Institute, Göteborg University.

Fröderström, H. (1936). The genus Sedum L. : a systematic essay. Part. IV. Acta Horti Gotoburgensis. 10, Appendix. 1-181 + pl. I-CXV.

Pilbeam, J. (2008). The genus Echeveria. The British Cactus & Succulent Society, Hornchurch. 333 pp.

Walther, E. (1972). Echeveria. California Academy of Sciences, San Francisco. pp. 426.

Crassulaceae, G.E. Wickens. Flora of Tropical East Africa. 1987

Morphology General Habit

Annual, biennial or perennial herbs, rarely small shrubs, usually succulent

Morphology Leaves

Leaves opposite or alternate, rarely verticillate, exstipulate

Morphology Reproductive morphology Flowers

Flowers usually in terminal cymose inflorescences, less often in spikes or racemes or solitary in the leaf-axils, with or without bracts, regular, hermaphrodite, rarely unisexual and dioecious, mostly (3–)4–5(–±30)-merous

Morphology Reproductive morphology Flowers Calyx

Sepals free or united into a tube, persistent

Morphology Reproductive morphology Flowers Corolla

Petals the same number as the sepals, free or variously connate

Morphology Reproductive morphology Flowers Androecium

Stamens hypogynous or epipetalous, as many as the petals or twice as many, and in 2 whorls, frequently obdiplostemonous; filaments free or adnate to the petals; anthers 2-thecous, introrse, opening by a longitudinal slit; scale-like nectaries usually present between the stamens and carpels

Morphology Reproductive morphology Flowers Gynoecium

Carpels superior, equal in number to the petals, free or slightly connate at the base, 1-locular; ovules (few–)many, inserted on the adaxial suture; style short or elongated, stigmatose on the inner side of the apex

Morphology Reproductive morphology Fruits

Fruit follicular, membranous or leathery, often surrounded by the persistent membranous corolla, opening on the adaxial side

Morphology Reproductive morphology Seeds

Seeds minute; endosperm usually present; embryo straight

Crassulaceae, R. Fernandes. Flora Zambesiaca 7:1. 1983

Morphology Leaves

Leaves opposite, verticillate or alternate, usually simple, sometimes compound, exstipulate, often ± thick and fleshy-succulent

Morphology Reproductive morphology Flowers

Flowers (3)4-5(6-32)-merous, actinomorphic, usually bisexual, in axillary or terminal cymes often grouped in corymb- or panicle-like inflorescences, less often in racemes or spikes or solitary in the leaf-axil

Morphology Reproductive morphology Flowers Calyx

Sepals free or ±: united at the base, sometimes in a ± long tube

Morphology Reproductive morphology Flowers Corolla

Petals as many as the sepals, free or ± connate, hypogynous

Morphology Reproductive morphology Flowers Androecium

Stamens as many or twice as many as the petals; filaments free or more or less connate with the corolla-tube; anthers 2-celled, introrse, basifixed, dehiscing longitudinally

Morphology Reproductive morphology Flowers Gynoecium

Ovary superior; carpels equal in number to the petals, free or united (up to the middle); ovules many or few to one in each carpel, anatropous, inserted on the adaxial suture; styles short, sometimes nearly absent or ± elongate; stigmas capitate

Morphology Reproductive morphology Fruits

Fruit follicular, membranous or leathery, opening along the free part of the adaxial suture

Morphology Reproductive morphology Seeds

Seeds mostly minute with smooth, rugose or tuberculate tegument and usually fleshy endosperm; embryo straight

Morphology Reproductive morphology Flowers Nectaries

Hypogynous scales (scale-like nectaries) usually present, small, applied to the base of the outer face of the carpels