Key to Genera
A. Flower-tube bent; stamens long-exserted 1. Denmoza (p. 78)
AA. Flower-tube straight, usually with a broad throat; stamens included. B. Ovary and fruit naked. (See Copiapoa.) Plants spineless, except seedlings.
Tubercles prominent, cartilaginous, flattened, more or less imbricated 2. Ariocarpus (p. 80)
Tubercles low, rounded above 3. Lophophora (p. 83)
Plants very spiny.
Fruit crowned by sepal-like scales 4. Copiapoa (p. 85)
Fruit naked at to!). Fruit dry.
Spines acicular 5. Pediocactus (p. 90)
Spines flat, papery 6. Toumeya (p. 91)
Fruit fleshy, indehiscent 7. Epithelantha (p. 92)
BB. Ovary and fruit scaly.
C. Flowers funnelform, often with a slender tube. Axils of flower-scales hairy or bristly.
Axils of flower-scales with bristles and hairs 8. Neoporteria (p. 94)
Axils of flower-scales with hairs only.
Flowers long-funnelform 9. Arequipa (p. 100)
Flowers short-funnelform 10. Oroya (p. 102)
Key to Genera—continued.
Axils of flower-scales naked.
Tube of flower longer than limb, its scales not fimbriate; spines all straight 11. Matucana (p. 102)
Tube of flower not longer than limb, its scales fimbriate; central spine hooked 12. Hamatocactus (p. 104)
Tubercles short, imbricated, much as in Ariocarpus 13. Strombocactus (p. 106)
Tubercles much elongated, slender, finger-like 14. Leuchtenbergia (p. 107)
DD. Areoles arranged on definite ribs.
E. Scales of ovary and perianth-tube entire (except in some large species of Ferocactus). F. Axils of scales on ovary and fruit naked.
Ribs usually continuous, rarely if ever tubercled; flowers with scarcely any tube.
Ribs usually numerous, much compressed and thin 15. Echinofossulocactus (p. 109)
Ribs not so numerous, usually thick 16. Ferocactus (p. 123)
Ribs usually broad, tubercled; flowers with a short but definite tube.
Spines or most of them acicular; flowers purple; seeds muricate 17. Echinomastus (p. 147)
Spines stout, mostly subulate; flowers white, yellow, or pink; seeds tuberculate 18. Gymnocalycium (p. 152)
FF. Axils of scales on ovary hairy, woolly or setose. Ovary-scales many, their axils woolly.
Axils of scales on flower-tube neither bristly nor spiny. Ribs several to many; plants very spiny.
Fruit permanently woolly, nearly dry, dehiscent by a terminal lore 19. Echinocactus (p. 166)
Fruit not so woolly, bursting irregularly, somewhat fleshy 20. Homalocephala (p. 181)
Ribs few, broad; plants mostly spineless 21. Astrophytum (p. 182)
Axils of scales on flower-tube usually bristly or spiny as well as woolly.
Top of fruit spinose; seeds pitted 22. Eriosyce (p. 186)
Top of fruit not spinose; seeds not pitted. Seeds not shell-like; plants mostly large. Spines straight or rarely curved; seeds with truncate base 23. Malacocarpus (p. 187)
Spines acicular, one of centrals strongly hooked;
Seeds shell-like; plants very small 25. Frailea (p. 208)
Ovary-scales few, their axils with tufts of short hairs.
Fruit a berry; spines all straight 26. Mila (p. 211)
Continue reading here: Denmoza gen nov
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