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Systematic Occurrence of a Sclerotic Hypodermis in Roots of Araceae

1987; Wiley; Volume: 74; Issue: 6 Linguagem: Inglês

10.2307/2443870

1537-2197

James C. French,

Plant Reproductive Biology

A survey of the systematic occurrence of a sclerotic hypodermis was made in 91 genera and over 280 species of Araceae. The sclerotic hypodermis in roots consists of a cylinder inside the exodermis, one to five or more cells wide, with thickened, lignified cell walls. The cells are elongated, pitted, and often septate. A sclerotic hypodermis occurs in roots of only eight genera of Araceae, including Culcasia, Montrichardia, Cercestis, Rhektophyllum, Furtadoa, Homalomena, Philodendron, and Anubias. In Philodendron section Philodendron a sclerotic hypodermis is present in aerial and absent from subterranean roots. These results are consistent with other anatomical studies in supporting a transfer of Culcasia from Pothoideae, and Cercestis, Rhektophyllum, and Montrichardia from Lasioideae into an expanded Philodendroideae, as recently proposed by Grayum. Further, these and other anatomical results both provide support for a closer taxonomic association of Culcasia, Cercestis, Rhektophyllum, Philodendron, Montrichardia, Homalomena, Anubias, and Furtadoa than has previously been recognized.