Mahonia repens

Mahonia repens Obaberine, obamegine, oxyacanthine, thalrugosine 198... 

Hydrastis canadensis rhizome, root Mahonia aquifolium root Mahonia nervosa root Mahonia repens root Phellodendron amurense bark Phellodendron chinense bark Sanguinaria canadensis rhizome, root... 

Three common subalpine species were selected Mahonia repens, Rumex densiflorus and Populus tremuloides. Mahonia repens is a low stature understory shrub with horizontal foliage. Rumex densiflorus and Populus tremuloides, an open-growing herb and tree, respectively, have primarily vertical leaf orientation. Plants grew in an Artemisia-dominated forest opening and in the adjacent understory of a dense stand of Pinus contorta at ca. 300 m in the Medicine Bow Mountains, Wyoming. The forest opening and understory were selected... 

For species that occurred in both light environments leaf angle was considerably steeper in the open versus understory (Fig. 1). Mean leaf angle for Populus tremuloides in the open and understory were 58.2 and 37.9°, respectively, and 33.9° and 16.9°, respectively, for Mahonia repens. Rumex densiflorus did not grow in shaded habitats. 

Our preliminary results suggest at least three possibilities regarding the functional symmetry of leaves. 1) Vertically oriented leaves of Populus tremuloides are functionally bilateral, thus contributing to maximum light capture as solar angle varies during the day. 2) Horizontally oriented leaves of Mahonia repens are functionally uilateral at low irradiances but become symmetrical as irradiance increases, whereas 3) foliage of Rumex densiflorus is functionally unilateral at all irradiances. Unilateral function of understory leaves of M. repens may be associated with structural and biochemical attributes that maximize photosynthesis at low irradiance. 

Figure 1. Frequency distributions of leaf angles (0 horizontal) for Populus tremuloides, Mahonia repens, and Rumex densiflorus. Measurements were made on plants growing in the forest understory (filled bars) or in an adjacent opening (striped bars).

Figures 2, 3, and 4. The response of net photosynthesis (A), stomatal conductance (gL), and intercellular CO2 concentration (C ) to incident irradiance when leaves were illuminated on the adaxial (solid line) or abaxial (dashed line) leaf surface. Figure 2 Populus tremuloides Figure 3- Mahonia repens Figure 4 Rumex densiflorus.

Grace, S.C., Logan, B.A. Adams, W.W. (1998a). Seasonal differences in foliar content of chloro-genic acid, a phenylpropanoid antioxidant, in Mahonia repens. Plant, Cell Environment, 21,... 

Suess TR, Stermitz FR 1981 The constituents of Castilleja rhexifolia, Mahonia repens and Oncidium cebolleta. Diss Abstr Int B 42 1025-1026... 

Suess TR, Stermitz FR 1981 Alkaloids of Mahonia repens with a brief review of previous work in the genus Mahonia. J Nat Prod 44 680-687... 

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