Pediocactus

Pediocactus (Greek: πεδίον (pedion) means "plain", "flat", "field") is a genus of cacti. The genus comprises between 6 and 11 species, depending upon the authority. Species of this genus are referred to as hedgehog cacti, though that name is also applied to plants from the genera Echinocereus and Echinopsis. Species may also be referred to as pincushion cacti, a common name which is also applied to other genera.

Description
The Pediocactus genus includes small species of cactus that grow either individually or in clusters, reaching heights of up to 20 cm. The shoots, which can be green or glaucous, come in cylindrical, spherical, or depressed spherical shapes, with diameters ranging from 1 to 15 cm and heights from 0.7 to 20 cm. Despite lacking ribs, these shoots have warts measuring 2 to 12 mm in length and 2 to 11 mm in diameter. The characteristic appearance is contributed to by the areoles, spaced 1 to 6 mm apart (occasionally up to 12 mm). The shoots also have thorns, varying in number, color, and orientation. There can be up to ten light gray or white central spines, measuring 0.5 to 3.2 cm, and three to 35 reddish to whitish marginal spines, which can be straight, curved, or comb-shaped, extending 0.1 to 2.1 cm in length.

The bell-shaped flowers at the top of the shoots come in colors ranging from yellow to magenta to white, with diameters of 1 to 2.5 cm. The flowers are characterized by a glabrous or nearly glabrous pericarpel and a short floral tube. Flowering typically occurs in spring, but certain species form buds in late autumn, with some capable of flowering even in their juvenile stages.

The fruits, initially greenish and cylindrical to spherical, transform into reddish-brown, dry structures upon ripening. Opening with a vertical gap, the fruits may be bare or possess a few scales. As the fruit opens, the remaining flower partially detaches, leaving a residue resembling a cap. The fruits contain blackish-brown, wrinkled to tuberous, obovate, or pear-shaped seeds. These seeds ripen 4 to 6 weeks after flowering and remain viable for an exceptionally long period, lasting at least 10 years.

Species
, Plants of the World Online accepts the following species:

Synonyms
The genus has 3 synonyms:
 * Navajoa Croizat
 * Pilocanthus B.W.Benson & Backeb.
 * Utahia Britton & Rose

Sclerocactus and Pediocactus were also at one time reduced to synonymy, but this is not at present considered to be correct.