PLUMBAGINALES

the plumbago, or leadwort, order of dicotyledonous flowering plants comprising the family Plumbaginaceae, with 10 genera of herbs and shrubs, found throughout the world but especially in semi-arid salt steppes and seacoasts of Europe, Asia, Africa, and Australia. The plants are characterized by alternating, simple leaves that often bear glands on the surface and by radially symmetrical, bisexual flowers, the petals of which are fused into a tube, and the sepals of which remain attached to the fruit until maturity. The male flower parts (stamens) number five and arise from the inner surface of the corolla (fused petal tube) opposite the petal lobes. The female structure (pistil) is superior, i.e., positioned above the other flower parts, and is composed of five carpels (structural segments), which enclose one chamber containing a single ovule. The upper part of the pistil consists of five more or less united styles topped by their stigmas, the pollen-receptive surfaces. The largest genera include Limonium (300 species), Acantholimon (150 species), Armeria (80 species), Plumbago (12 species), Limoniastrum (10 species), and Ceratostigma (8 species). The remaining four genera (Dyerophytum, Aegialitis, Plumbagella, and Limoniopsis) contain only one or two species each. Thrift (Armeria) Sea lavender (Limonium vulgare) growing with glasswort (Salicornia europaea). Economically the group is important mainly for the many garden ornamentals it contains. Among these are a number of species of Armeria that go by the common name thrift, especially A. maritima, also called sea pink, a plant with small red flowers that is common on sea cliffs and in high mountains in western Europe. Sea lavender (Limonium vulgare; see photograph), with small flowers in dense spikes, grows in large tracts that sometimes turn acres of ground lilac-coloured during the late summer blooming season. The flower spikes of L. vulgare and other Limonium species, also known as sea lavender, are often used in dry-flower arrangements for their lasting qualities and permanent colours. Prickly thrifts (species of Acantholimon, especially A. glumaceum) are favourite rock-garden plants. The sap of leadwort (Plumbago europea) is irritating and caustic, as are the juices of other Plumbago species, for example, P. indica (or P. rosea) and P. scandens, which are grown in the cool greenhouse for their rose and white or blue flowers, respectively. The leaves and roots of P. zeylanica have been used as a remedy for skin disease, especially in the tropical Far East. The active principle extracted from Plumbago roots, used in several medicinal drugs, is a yellow pigment called plumbagin.