Squill — Scilla (squill) is a genus of bulb-forming perennial herbs in the Hyacinthaceae. The 90-odd species are found in woodlands, subalpine meadows, and seashores across the Old World. Their flowers are usually blue, but white, pink, and purple types are known; most flower in early spring, but a few are autumn-flowering. Several African species previously classified in Scilla have …

Snapdragon — Antirrhinum is a genus of plants more commonly known as snapdragons from the flowers’ fancied resemblance to the face of a dragon that opens and closes its mouth when properly squeezed (thus the ‘snap’). The antirrhinums used to be treated as the family Scrophulariaceae, but studies of DNA sequences have led to the inclusion of Antirrhinum in a …

Shamrock — Shamrock is the common name for several unrelated herbaceous plants with trifoliate leaves. White clover, Trifolium repens forma minus, family Leguminosae, was the original shamrock of Ireland; Trifolium procumbens is now commonly used. Saint Patrick used the shamrock leaf to symbolize the Trinity, and a trifoliate leaf of this shamrock is worn by the Irish on March 17 …

Senna — Senna (from Arabic sana), the sennas, is a large genus of around 250 species of flowering plants in the family Fabaceae, subfamily Caesalpinioideae. This diverse genus is native throughout the tropics, with a small number of species reaching into temperate regions. Almost all species were at one time or another placed in Cassia, a close relative which until …

Saint-John’s-Wort — St John’s wort used alone refers to the species Hypericum perforatum, also known as Tipton’s Weed or Klamath weed, but, with qualifiers, is used to refer to any species of the genus Hypericum. Therefore, H. perforatum is sometimes called Common St John’s wort to differentiate it. The species of Hypericum have been placed by some in the family …

Poppy — A poppy is any of a number of showy flowers, typically with one per stem, belonging to the poppy family. They include a number of attractive wildflower species with showy flowers found growing singularly or in large groups; many species are also grown in gardens. Those that are grown in gardens include large plants used in a mixed …

Pokeweed — The pokeweeds, also known as poke, pokebush, pokeberry, pokeroot, polk salad, polk sallet, inkberry or ombú, comprise the genus Phytolacca, perennial plants native to North America, South America, East Asia and New Zealand. Pokeweed contains phytolaccatoxin and phytolaccigenin, which are poisonous to mammals. However, the berries are eaten by birds, which are not affected by the toxin because …

Poison Sumac — Poison sumac (Toxicodendron vernix or Rhus vernix) is a woody shrub or small tree growing to 7 m (20 ft) tall. All parts of the plant contain a resin called urushiol that causes skin and mucous membrane irritation to humans. When burned, inhalation of the smoke causes diarrhea and other internal irritations. The head of the tree …

Poison Hemlock — Conium is a genus of two species of perennial herbaceous flowering plants in the family Apiaceae, native to Europe and the Mediterranean region (C. maculatum), and to southern Africa (C. chaerophylloides). By far the most familiar species is Conium maculatum (Hemlock or Poison Hemlock), the most common of several species of hemlock noted for their toxicity. It …

Poinsettia — Poinsettias (Euphorbia pulcherrima) are flowers of Mexican origin, native to the Pacific coast of the United States, some parts of central and southern Mexico (including the Mexican Pacific coast), and a few localities in Guatemala. They are named after Joel Roberts Poinsett, the first United States Ambassador to Mexico (technically first U.S. envoy to Mexico), who introduced the …