Orach

Annual herbs, subshrubs or shrubs, monoecious or dioecious, covered with bladder hairs having short basal cell and globular terminal cell; occasionally, other hair types (simple bristle-like or curved hairs) can be detected under higher magnification. Leaves alternate or opposite, simple, flat, petiolate. Inflorescence leafy or not, consisting of few or numerous flowers that are usually unisexual. The male and bisexual flowers are enclosed by (3–4)5 green perianth segments that remain unchanged at fruiting in bisexual flowers; female flowers enclosed by two accrescent perianth segments [valves] (often called ‘bracteoles’ or bract-like cover) that are free or connate to varying degrees. Seeds have a vertical embryo, some seeds rarely with horizontally orientated embryo. Often (in annual species) heterospermy is present (seed coat black and brown/red). The largest genus amongst the Chenopodiaceae (~260 species).