Opuntia caesia

Opuntia caesia
Opuntia caesia

Griffiths, Proceedings of the Biological Society of Washington 29(3): 13–14, 1916

Isotype; Herbarium; Herbarium; Herbarium; Herbarium

Original Citation 

What is Opuntia caesia?

Opuntia caesia is a prickly pear cactus that is larger than O. phaeacantha. It may reach 2-3 m across and be about 60-80 cm tall with erect branches that rise from spreading, sprawling branches.

Details

The main branches often rest on the ground with upright branches to 60(70) cm. Cladodes on this Opuntia are typically 11-15 cm wide by 20-24 cm long, though they are variable. The obovate pads may have a narrow base. New growth is glaucous and blue-green but becomes yellowish-green in age. There are 2-4 spines in the first year that are sometimes dark but which may be nearly white. The longest spines can be 5(8) cm long. 

The flower is yellow brushed with red in the interior. The style is white and the stigma is globose and light green; filaments are yellow with greenish bases. The ripe fruit is purplish-red but the pulp is lighter. 

Ploidy is unknown. 

Other Notes

Griffiths remarked that this Opuntia has nearly as much glaucous blue bloom as O. robusta. The blue color fades to greenish or yellow-green under drought stress or with age. 

The plants are abundant around Crozier, Arizona. They may be low in Crozier but are taller in Toquerville, Utah. The Opuntia shares similarities with O. camanchica and O. phaeacantha, but the blue color makes it distinctive. When O. phaeacantha and O. caesia are growing together the first usually has smaller pads with more areoles, and it definitely has less woody growth. Intermediates are not found. 

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