Distribution of the Dimorphic Hypodermis of Roots in Angiosperm Families

The dimorphic hypodermis is composed of two lands of cells differingin size and staining properties, often alternating in a regularpattern. The roots of 98 of 358 genera examined for the presenceof a dimorphic hypodermis had one and 97 additional genera witha dimorphic hypodermis were compiled from the literature. Thehypodermal type of the root was found to be a fairly constantcharacteristic at the family level. Forty-one angiosperm familieshad members with a distinct dimorphic hypodermis. A dimorphichypodermis was found both in families with many specializedcharacteristics such as the Orchidaceae and in families whichhad many unspecialized characteristics such as the Magnoliaceae. Angiosperms, hypodermis, roots