Micromorphological characteristics and systematic evolutionary significance of Impatiens paradoxa C. S. Chu et H. W. Yang (Balsaminaceae)

The micromorphological characteristics of the leaf epidermis and pollen of Impatiens paradoxa C. S. Chu et H. W. Yang were observed by light microscopy (LM) and scanning electron microscopy (SEM). Results showed the following:there was no stomatal apparatus on the upper epidermis; epidermal cells were irregularly polygonal in shape with undulate anticlinal walls; the external upper epidermis were small lattices formed by cell wall protrusions of adjacent cells, with stripe ornamentation outside the circular protrusion; lower epidermis contained elliptical stomatal apparatus with two guard cells; lower epidermal cells were irregularly polygonal in shape with sinuate anticlinal walls; external lower epidermal cells contained small lattices with circular protrusions and stripe ornamentation, especially with fusiformis structure; pollen was single-grain, oblong in polar view, long elliptical in long equatorial view, short elliptical in short equatorial view, with four germinal furrows in the angular position, which were slender, short, and shallow; and outer pollen wall showed reticulate ornamentation, with prominent granules in the lumina at different densities. This article discusses the significance of external, leaf epidermis, and pollen morphology of an endemic species, which is considered a highly specialized group. Thus, with its large yellow flower, I. paradoxa could be used as an excellent ornamental plant. The natural distribution of I. paradoxa also indicates similarity in the flora of the Funiu and Qinling-Daba mountains.