Subfamilial Classification of Labiatae

A subfamilial level classification of Labiatae, originally proposed by G. Erdtman on the basis of pollen features, has received substantial corroboration in the European literature but remains little known in North America. In subfam. Lamioideae, pollen is usually tricolpate and shed in a two-celled stage; in subfam. Nepetoideae (Dumortier) Luerssen, it is usually hexacolpate and shed in a three-celled stage. The number of pollen cells and colpi are reported here for 108 genera of Labiatae, including 93 for which one or both had not previously been reported. The established relationship between number of colpi and pollen cells is consistent in 95% of the labiate genera for which data are available. In the remaining genera, one pollen character is constant while the other varies; in no genus is the pollen consistently tricolpate and three-celled when shed or consistently hexacolpate and two-celled. Other characters whose variation patterns closely parallel the pollen characters include occurrence of endosperm, embryo shape, cotyledon shape, volatile terpenoid content, occurrence of rosmarinic acid, occurrence of iridoid glycosides, degree of un- saturation of fatty acids in the seed oils, and myxospermy. Erdtman's subfamilies appear to be the primary phenetic groupings of the Labiatae, but only subfam. Nepetoideae can be shown to be monophyletic on the basis of synapomorphies. Briquet's (1895-1897) widely used classification is highly incongruent with Erdtman's, and it is recommended that the former be abandoned. A tabulation is provided of the component genera of each of Erdtman's subfamilies, along with the character state data upon which subfamilial assignments were based.

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