Colletia

Colletia is a small genus of thorny, evergreen shrubs in the family Rhamnaceae, native to southern South America, including Argentina, Chile, Uruguay, and parts of southern Brazil. The plants are valued for their striking, spiny form and are commonly known as anchor plants due to the distinctive shape of their branch architecture. Leaves, when present, are usually very small or shed early, with the stems taking over photosynthesis.

Description and habit: Colletia species are typically shrubs or small trees with rigid, spiny branches. They often have reduced leaves or none at all, giving a compact, architectural appearance. Flowers are small, usually white or pale, and appear in clusters on the tips of branches in spring or summer. Fruits are small drupes or berries that develop after flowering and persist on the plant into autumn or winter.

Taxonomy and distribution: The genus belongs to Rhamnaceae and includes several described species, the most well known being Colletia paradoxa (often cited in horticulture as the anchor plant). Taxonomic treatments have varied, and some species historically placed in Colletia have been reassigned to related genera in modern classifications, so species placement can differ among authorities.

Cultivation and horticulture: Colletia paradoxa is cultivated as an ornamental in arid and semiarid climates for its sculptural silhouette and drought tolerance. It prefers full sun and well-drained soil, with relatively low water requirements once established. The plant is typically used in xeriscapes, hedges, or accent specimens and can be pruned to maintain desired shape.