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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

CACTACEAE CACTUS FAMILY

Bruce D. Parfitt, except as noted


Perennial herb, shrub, tree, generally fleshy. Stem: cylindric to spheric, or flat; surface smooth, tubercled, or ribbed (grooved); nodal areoles bearing flowers. Leaf: generally 0 or early-deciduous, flat to ± cylindric. Spines: areoles generally with central, radial spines, occasionally with glochids. Flower: generally 1 per areole, bisexual [unisexual], sessile, radial [bilateral]; perianth parts generally many [5], scale-like to petal-like; stamens many; ovary inferior [superior], style 1, stigma lobes generally several [many]. Fruit: dry to fleshy or juicy, indehiscent to variously dehiscent, spiny, scaly, or naked; tubercled or smooth. Seed: generally many, occasionally 0–few.
± 125 genera, ± 1800 species: America (especially deserts), Africa; many cultivated, some edible. [Parfitt & Gibson 2004 FNANM 4:92–257] Spines smaller, fewer (0) in shade forms; yellow spines blacken in age. Introduced species increasingly escape cultivation. Hybridization common in some genera. Taxa of Escobaria in TJM (1993) moved to Coryphantha. —Scientific Editors: Bruce D. Parfitt, Douglas H. Goldman, Bruce G. Baldwin.
Unabridged references: [Hunt 2006 The New Cactus Lexicon, DH Books, Milborne Port, England]

Key to Cactaceae

1. Stem regularly segmented; areoles with glochids; seeds tightly encased within bone-like aril, ± white when dry

2. Stem segments flat, tubercles 0 to ± developed; spine surface not separating ..... OPUNTIA

2' Stem segments cylindric to club-like, generally tubercled; spine surface sheath-like, generally separating and late-deciduous

3. Spines not flat; spine sheath 0 or fully separating; mature plant generally 0.3–4 m ..... CYLINDROPUNTIA

3' Major spines flat; spine sheath separating only from tip; mature plant generally < 0.25 m ..... GRUSONIA

1' Stem not regularly segmented; glochids 0; dry seeds generally black to ± red-brown, lacking a ± white bone-like aril

4. Largest spines with transverse ridges; spines generally 2–5 mm diam near base, rigid

5. Ovary, generally stem tip densely woolly, obscuring epidermis, ovary scales tapered to sharp tips ..... ECHINOCACTUS

5' Ovary, stem tip glabrous, only areoles woolly, ovary scales generally rounded ..... FEROCACTUS

4' Largest spines smooth or longitudinally ridged; spines generally < 2 mm diam near base, rigid or not, thin, flexible if > 2 mm wide

6. Stem ribs 0 or inconspicuous, tubercles prominent

7. Spines all straight to ± curved; stem tubercles with woolly, adaxial groove connecting spine cluster to axillary flower areole ..... CORYPHANTHA

7' Some spines in each areole generally hook-shaped; stem tubercles not adaxially grooved ..... MAMMILLARIA

6' Stem ribs prominent, tubercles ± 0 or prominent on ribs

8. Stem > 30 cm diam, branched but generally not in basal 1.5–2 m; perianth generally white ..... CARNEGIEA

8' Stem < 15 cm diam, not branched, or branched in basal 1.5 m; perianth variously colored, but generally not white

9. Stem length > 8 × diam; fruit persistent when empty, densely spiny; coastal ..... BERGEROCACTUS

9' Stem length < 6 × diam; fruit not persistent when empty, spineless or spines deciduous; inland

10. Flowers lateral; ovary minutely scaly, spiny, spines deciduous in clusters; stem soft-fleshy, branches 1–500 ..... ECHINOCEREUS

10' Flowers at stem tip or nearly so; ovary scaly, spineless; stem ± hard, branches 0–few (more if stem damaged) ..... SCLEROCACTUS

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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