Pterocactus fischeri sp nov

Stems low, 1 dm. high or less, spreading or erect, cylindric, 1.5 cm. in diameter, tuberculate; leaves minute, acute; tubercles about as long as broad, arranged in spiral ridges somewhat resembling those of Opuntia whipplei; spines numerous, the radials 12 or more, white, setaceous, 6 mm. long, spreading; centrals usually 4, 1 to 1.5 cm. long, brownish, the tips and bases often yellowish;

35 36

Seeds of three species of Pterocactus. Natural size.

glochids numerous, yellowish, 3 to 4 mm. long; flowers, in only specimen seen, terminal, almost continuous with the stem; ovary tuberculate and spiny like the stem, deeply umbilicate; seed one, large, flat-winged.

Collected by Walter Fischer in 1914. in the Province of Rio Negro, Argentina, and given to Dr. Rose during his visit to Argentina in 1915 by Professor Cristóbal M. Hicken.

While this species resembles some of the species of Cylindropuntia of the United States, the spines are not sheathed.

Figure 33 is from a photograph of the specimen above cited; figure 34 shows a seed of the same specimen.

Continue reading here: Pterocactus tuberosus Pfeiffer

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