The morphology and anatomy of proteoid roots in the genus Hakea

Abstract

This paper extends the introductory work of Purnell(1960) on proteoid roots in the family Proteaceae by a detailed study of the genus Hakea, with special reference to H. prostrata. The presence of proteoid roots is reported in 63 Hakea species. Their relative contribution to the root system is related to such plant factors as species, age, and cotyledon size. The dimensions of proteoid roots are dependent on plant age and species. The morphology and anatomy of these structures are described. Endophytic microorganisms are not normally associated with proteoid roots. Proteoid rootlets survive 2-3 months, though their parent roots last indefinitely.

Proteoid roots are produced by the youngest roots in the root system. While proteoid rootlets arise laterally, the parent root may arise either laterally or adventitiously. Both proteoid and non-proteoid roots may be initiated within a proteoid root.