Taxonomy of the Polygonum douglasii (Polygonaceae ... - WLU

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4 BRITTONIA [VOL. 57 FIG. 2. Micromorphology of leaves. A–D. Margin of the leaf. A. Polygonum sawatchense subsp. sawatchense (scale bar � 0.3 mm). B. P. utahense (scale bar � 0.3 mm). C. P. sawatchense subsp. oblivium (scale bar � 100 �m). D. P. spergulariiforme (scale bar � 100 �m). E, F. papillae on the leaf blade: E. P. spergulariiforme. F. P. utahense (scale bars � 30 �m).
2005] COSTEA & TARDIF: POLYGONUM DOUGLASII COMPLEX 5 lobes are oblong-elliptic to oblong-obovate, often cucullate and overlapping, naviculate along their entire length or only in the upper 1/4 (Fig. 3). Vasculature of tepals consists of a single vein, which may be branched or not. EPICUTICULAR WAX PATTERN OF PERIANTH LOBES Epidermis cells are irregularly shaped, elongated or rectangular (Figs. 4, 5). Stomata are usually present. The anticlinal walls are usually sinuate or sometimes straight or weakly undulate (Figs. 4, 5). Epicuticular wax sculpture pattern is variable and complex: Type 1. Epidermis cells with the periclinal walls more or less flat. Sculpture pattern is homogenous on the same cell. Wax rodlets may be arranged in a dense reticulate, intertwined pattern (Figs. 4C, 5E, F) or they may be more or less transversally oriented (Fig. 4A, B). Type 2. Epidermis cells with the periclinal walls evidently convex. Sculpture pattern is heterogeneous on the same cell: wax rodlets are � parallel among themselves and perpendicular to the long axis of cells on the lateral inclined faces and arranged in a dense reticulate and intertwined pattern on the more or less flat top of the periclinal walls (Fig. 4D–F, 5A– D). STAMENS Stamens are most commonly eight, arranged in two ‘‘whorls.’’ The outer whorl consists of five stamens and the inner of three stamens. Stamens in the outer ‘‘whorl’’ may be reduced, sometimes entirely (e.g., P. sawatchense subsp. sawatchense). The base of the inner stamens is thickened and associated with a nectarial tissue. Anthers are short, 100–550 �m, pink to purple, rarely whitish. POLLEN The pollen belongs to the ‘‘Duravia type’’ described by Hedberg (1946). It is prolate, usually tricolporate with the exine semitectate-reticulate or microreticulate at the mesocolpia and poles, and microreticulate-foveolate or sometimes foveolate with microspinules around ectoapertures (Fig. 6). Two distinct types can be recognized based the size of the pollen grains, the reticulum sculpturing at the middle part of the mesocolpium and the sculpturing of ectoapertures: Type A. Pollen grains 20–26 �m long; mesocolpium is microreticulate with 1–7 rows of lumina, 0.5–1(–1.1) �m indiameter, clearly differentiated or undifferentiated from the ectoapertures, which are microreticulate to tectate perforate, foveolate-punctate, sometimes with microspinules. ● Subtype A1.—Mesocolpium is microreticulate and not clearly differentiated from the ectoapertures. Mesocolpium microreticulum with 4–7 rows of lumina, 0.5–0.9 �m in diameter (Fig. 6A–C). ● Subtype A2.—Mesocolpium is reticulate, clearly differentiated from ectoapertures. Mesocolpium reticulum with 1– 5 rows of lumina, 0.9–1.1 �m in diameter (Fig. 6D, E). Type B. Pollen grains 28–33 �m; mesocolpium is reticulate with 1–2 rows of lumina, 1.5–4 �m in diameter; mesocolpium is sharply differentiated from the ectoapertures, which are tectate imperforate, rarely punctate, with a few puncta (Fig. 6F–H). ACHENES Achenes are black, trigonous, ovate, ovate-lanceolate, elliptic, and enclosed in the perianth or exserted at maturity (Fig. 7). Faces are concave and subequal; one face is slightly broader than the other two (Fig. 7). The exocarp is usually lustrous and smooth, or sometimes it may be striate-tubercled, especially near the edges and apex of achenes (Fig. 7C, F). Tubercles may be arranged in longitudinal rows, more or less following the anticlinal walls (Fig. 7D). Taxonomy Hickman (1984) included within P. douglasii five other species that share a significant area of sympatry: P. sawatchense
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Taxonomy of the Polygonum douglasii (Polygonaceae ... - WLU

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