Cryosophila is a genus of medium-sized fan palms that range from central Mexico to northern Colombia. Species in the genus can be readily distinguished from related genera by their distinctive downward-pointing spines on the stem, which are actually modified roots. They are known as the "root spine palms". Description Cryosophila is a genus of medium-sized, single-stemmed (or rarely multi-stemmed) palms with fan-shaped (or palmate) leaves and spiny stems. The stems range in height from , with diameters between . Plants have between five and 35 leaves with elongated petioles. The leaves are often whitish-grey on the lower surface. The whitish flowers are bisexual with six stamens and three carpels. The fruit are white and smooth, with a single seed. Cryosophila is distinguished from related genera by its long, branched spines which are derived from modified roots. These downward-pointing spines cover the trunk, often quite densely. The genus is one of the few palms which use modified roots as spines, and its spines are unlike any others in morphology or appearance. The density of spines varies from less than 25 over a length of stem in some species to others where the entire stem is covered by a dense mass of spines. Taxonomy In the first edition of Genera Palmarum (1987), Natalie Uhl and John Dransfield placed the genus Cryosophila in subfamily Coryphoideae, tribe Corypheae and subtribe Thrinacinae Subsequent phylogenetic analyses showed that the Old World and New World members of Thrinacinae are not closely related. As a consequence, Cryosophila and related genera were places in their own tribe, Cryosophileae. Within this tribe, Cryosophila appears to be most closely related to the genus Schippia. History The earliest botanical description of the species in the genus were made by Alexander von Humboldt, Aimé Bonpland and Carl Sigismund Kunth in 1816. They named two species, Corypha nana and Chamaerops mocini. Although these species were placed in different genera (both of which are now considered to be restricted to the Old World), today they are both thought to represent the same species—Cryosophila nana. In 1838 or 1839 Carl Ludwig Blume coined the name Cryosophila specifically for C. nana, but did not actually publish the combination and it was only validated in 1887 with the publication of Blume's combination by Carl E. Salomon in 1887. German botanist Hermann Wendland established a new genus, Acanthorrhiza, in 1869. He included two species in the genus, A. aculeata,