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Russian Pigweed (Axyris amaranthoides)

Description

Axyris amaranthoides is a species of vascular plant, in the family Amaranthaceae, that has been introduced to North America. It was introduced into Manitoba in 1886 and has since spread to other provinces in Canada and the United States. Axyris amaranthoides (2n=18) is commonly known as Russian pigweed and upright axyris A. amaranthoides is an annual monoecious (has both the male and female flowers in the same individual) plant. It has a taproot type of root system, and its stem is about 20–80 centimetres (8–31 in) tall and rigidly upright. The lower leaves have short petioles and have a narrowly oval to long-pointed shape. The upper leaves are narrowly lance-like to egg shaped, and attached directly to the stems or branches without petioles. The leaves on the main stems are much bigger than branch leaves, but all the leaves are serrated with slightly bent or curved backward or downward edges. A single leaf is present at each node along the stem, forming an ascending spiral pattern (alternate arrangement; see phyllotaxis). Male flowers grow on the top of stem in the form of slim spike. One or two female flowers grow from the leaf axils below the male flowers. Fruits are oval-shaped, reddish-coloured and dry (i.e., with thin pericarps). Some fruits are winged on one side and flattened, and will germinate rapidly. Other fruits are wingless, and tend to be dormant. The flowering time is in July and August.

Taxonomic tree

  • Domain: Eukarya

    • Kingdom: Plantae

      • Phylum: Magnoliophyta

        • Class: Magnoliopsida

          • Order: Caryophyllales

            • Family: Amaranthaceae

              • Genus: Axyris