Abstract
Qualitative and quantitative data are reported for seven specimens representing six varieties of the four species of Drimys generally recognized. Tracheid length and diameter are correlated both with plant size and with severity of climate: wide, long tracheids, not fluctuating in diameter seasonally, occur in Drimys of moderate elevations in subtropical latitude; narrower, shorter tracheids, becoming radially narrower briefly in latewood, occur in Drimys from higher altitudes and latitudes. Vesturing (warty layer) on the inside surface of tracheids occurs in Drimys from latitudes and altitudes where appreciable freezing is to be expected, but vesturing is absent at lower elevations and latitudes. Vesturing may bond water to tracheid walls better so that water columns do not break under high tensions produced by such conditions as transpiration when soil remains frozen. Scalariform pitting on end walls of Drimys tracheids occurs during the first year (metaxylem), but is replaced by alternate circular pits later; injury to the cambium, even of a mild kind, results in reversion to sca1ariform end wall pitting. Tracheid wall thickness is not correlated with tracheid diameter. Tracheid-ray pits are 75% the diameter of tracheid-tracheid pits. Axial parenchyma is sparse and diffuse (occasionally cells in tangential or radial pairs). Rays are Heterogeneous Type I; ray cells commonly have bordered pits on tangential walls. Silica bodies are reported (first report for Winteraceae) in rays of three collections of Drimys.
Highlights
Drimys S.s. has been treated as containing four species (Smith 1943), all of which are represented in the present study
Growth rings very weakly demarcated are present in D. brasiliensis (Irwin 126 78)
Scalariform pitting on end walls of tracheids is characteristically not present in Drimys, it is present in the winteraceous genera Zygogynum (Carlquist 1981), Bellio/um (Carlquist 1983a) and Bubbia (Carlquist 1983b)
Summary
Drimys S.s. has been treated as containing four species (Smith 1943), all of which are represented in the present study. The chromosome number in Tasmannia, X = 13, differs from the base number of all other Winteraceae (including Drimys) known cytologically, X = 43 (Ehrendorfer, Krendl, Habeler, and Sauer 1968). Tasmannia is the only dioecious genus of Winteraceae (Smith 1943). These differences, in combination with the occurrence of Drimys only in the New World and Tasmannia only in the Old World, do seem to merit recognition at the generic level. Wood anatomy does tend to be more conservative than other anatomical features, the present study, together with one in progress on Tasmannia, will examine whether any wood details differentiate Drimys from Tasmannia.
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