Overview of Wheat Celosia
Celosia is a genus of edible and ornamental herbaceous annuals and perennials in the amaranth family (Amaranthaceae) native to Africa, North America and South America. Celosia spicata (sometimes listed as C. argentea var. spicata) is a summer annual or short-lived tender perennial (zone 9a to 11b) grown as an ornamental for its distinctive, erect flower spikes reminiscent of a sheaf of wheat, which is the origin of the common name “wheat celosia.”
Taxonomists have reclassified wheat celosia to Deeringia spicata, though the horticulture industry has been slow to embrace this change and this species is still most commonly offered as C. spicata.
D. spicata has an open, branched habit with strong stems, growing 2 feet wide and 3 or more feet tall. The alternate, medium to dark-green leaves may be mottled or tinged with burgundy. The 2 to 6 inch long leaves are smooth and entire, oval or lance-shaped, and strongly veined.
Other species of celosia commonly grown as ornamental annuals are C. cristata (crested cockscomb), with a crested inflorescence, and C. argentea (sometimes listed as C. plumosa), with fluffy, plume-like inflorescences. A few varieties of C. argentea, like the SOL™ series, are grown for use as foliage plants rather than for their flowers.
Beginning in mid-summer, erect cylindrical inflorescences form on the branch tips above the foliage. The terminal spikes may be red, pink, purple, or bicolored and often develop a metallic silver sheen on the calyxes that remain after the flowers fade. The hundreds of small flowers densely packed within each spike bloom from the bottom up, and the spike continues to elongate as additional flowers open along the spike so that early flower spikes can be many inches long by time the frost arrives. Blooming continues until frost, but the plants are sturdy enough that they can remain upright and attractive through late fall.
Source : wisc.edu