Opuntia Mill.

Leaves absent or if present then reduced and terete. Flowers sessile Opuntia
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Stem segments mostly more than 5 cm wide and 10 cm long
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Areoles with 1 or 2 spines at most, rarely more.
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Areoles with 1–2 long spines 1–4 cm long. Tree-like. Cumberland Plain. Weed, particularly near creeks. Introd. from S. America. Tree Pear O.monocantha
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Areoles mostly with no long spines but sometimes those near the margin with a single spine. Coast and Cumberland Plain. Coastal sand dunes; open forests. Introd. from America. Common Prickly Pear Opuntia stricta