Like the arboretum where this relatively rare variety of hedgehog cactus may be viewed, echinocereus boyce-thompsonii
is named after engineer and botanical researcher William Boyce Thompson (1869-1930). The plant was once classed as a variant of echinocereus fasciculatus
but is now considered a separate species; the main differences are that the central spine is longer, around 3 inches (occasionally up to 5), and lighter in color (yellowish-brown); also the flower buds are more green, less brown. Both species have relatively light spination, not obscuring the green stems.
Stems, up to ten per plant, are usually around 6 inches tall, sometimes up to twice this. In addition to the main spine, there may be one or two shorter central spines. Radial spines number between ten and 14. Flowers are large, up to 2.5 inches in diamater; they have purple tepals, yellow stamens and green stigma lobes.