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on exposed gray limestone ledges and outcrops forming low hillside. SYN: Petrogenia r. (per Austin/Staples, Brittonia Vol. 37, No. 3. 1985)
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on exposed gray limestone ledges and outcrops forming low hillside. SYN: Petrogenia r. (per Austin/Staples, Brittonia Vol. 37, No. 3. 1985)
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on blockly limestone hillside.
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on limestone ledges of low hillside slope with Cactus species, Hechtia texensis.