Jepson eFlora
Key to families | Table of families and genera

Key to Cactaceae

View taxon page for 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 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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