Mammillaria tetrancistra
Corkseed pincushion cactus
© 2010 Lynn Reves
Pen and ink

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Plate Descriptions

1.   Habit
2.   Fruit between two tubercles
3.   Aerole with hooked central spines and bristle-like radial spines
4.   Seed
5.   Flower
6.   Flower - longitudinal section