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ANATOMY AND AFFINITIES OF PENTHORUM
Author(s) -
Haskins Melanie L.,
Hayden W. John
Publication year - 1987
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1987.tb08594.x
Subject(s) - saxifragaceae , biology , tracheid , xylem , synapomorphy , anatomy , botany , perforation , affinities , phylogenetics , clade , biochemistry , materials science , gene , metallurgy , punching
The genus Penthorum L. consists of two species of perennial herbs, P. sedoides of eastern North America and P. chinense of eastern Asia. Penthorum has long been considered intermediate between Crassulaceae and Saxifragaceae. An anatomical study of both species was undertaken to contribute to a better understanding of the relationships of these plants. Prominent anatomical features of Penthorum include: an aerenchymatous cortex and closely‐spaced collateral vascular bundles of stems; one‐trace unilacunar nodes; brochidodromous venation, rosoid teeth bearing hydathodes, and anomocytic stomata of leaves; angular vessel elements with many‐barred scalariform perforation plates and alternate to scattered intervascular pits; thin‐walled non‐septate fiber‐tracheids; abundant homocellular erect uniseriate and biseriate rays; and absence of axial xylem parenchyma. In general, Penthorum possesses neither the morphological nor the anatomical synapomorphies which define Crassulaceae, and features shared with Saxifragaceae are largely symplesiomorphous. Thus Penthorum is probably best classified in the monogeneric Penthoraceae.