Jepson eFlora: Key page
Vascular Plants of California
Key to families | Table of families and genera

Key to Cactaceae

View taxon page for Cactaceae


Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

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  to club-like, generally tubercled; spine surface sheath-like, generally separating and late-deciduous

3. Spines not flat; spine  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 epidermisovary scales  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  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  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



Citation for the whole project: Jepson Flora Project (eds.) . Jepson eFlora, [accessed on ]

Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on .

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