Amaranthaceae (amaranth family) contains a number of important plants. Species of saltbush (Atriplex) are extremely tolerant of environments with a high salt concentration and do exceedingly well near coastal areas. Sea orach (A. halimus) is cultivated for its beautiful foliage and silvery gray stems; its flowers are green and rather inconspicuous. Garden orach (A. hortensis) was at one time used as a cure for gout. Another interesting ornamental genus is Bassia, which includes summer cypress (B. scoparia) and burning bush (B. scoparia trichophylla); the leaves of the latter turn a beautiful red in autumn.

Cultivars of Beta vulgaris are vegetable crops, including the sugar beet and the garden beet, or beetroot. The beet’s leaves are similar in taste to spinach (Spinacia oleracea, of the same family). The root may be dark purplish red, yellow, white, or striped. It can be boiled or baked and is often pickled; in eastern Europe it is used in a soup called borsch. Cultivars include Forono, Cylindra, Boltardy, Detroit Dark Red, and Chioggia (a striped beet). Another cultivar, Swiss chard, is grown only for its leaves.

The goosefoot genus (Chenopodium) includes succulent herbs that commonly develop as weeds along seacoasts and salt marshes. Quinoa (C. quinoa) is a native of the Andes in South America and is cultivated as an important nutritious pseudograin crop.

The leaves of pigweed species (Amaranthus) are used as a leafy vegetable similar to spinach and can be made into a tea that is purported to have astringent properties and to cure dysentery, diarrhea, and ulcers. The word amaranthus is from the Greek for “unwithering,” and the plants were used as a symbol of immortality. Love-lies-bleeding (A. caudatus) is a Neotropical species that is often grown for its edible leaves and seeds as well as for its long pendant ropes of flowers.

Alligator weed (Alternanthera philoxeroides) was introduced into North America as a cultivated ornamental, but its rapid growth habit in watery environments has often caused it to be considered a weed. Globe amaranth (Gomphrena globosa) is from tropical Asia, Australia, and America. It is unusual in that the flower heads of tiny pink, white, or purple flowers are subtended by two coloured leafy bracts. Cockscomb (Celosia cristata) is an ornamental species.

Cactaceae

The cacti are curious, often thorny (spiny), succulent-stemmed plants constituting the family Cactaceae, characteristic of and well adapted to dry regions of the Western Hemisphere. Although all cacti are native to the Americas, except for a single species of Rhipsalis, they are cultivated widely throughout the world for their bizarre forms and often striking blossoms. Cacti are easily grown from cuttings or from seeds. Most are well adapted to warm, arid indoor conditions and require little care once established. Cacti are cultivated chiefly for their ornamental features and general hardiness. They can be grafted easily, and many rare species are propagated by grafting upon more vigorous stocks. Many small cacti are suitable for home cultivation. Without water, most cacti persist but do not grow. Some species, however, require periodic drought. Many species grow well in warm weather in full sun, provided there is adequate soil moisture, but others require some shade.

Cacti are economically important plants in Mexico, parts of Central and South America, and the Caribbean region. Various species are cultivated for food, including complexes of prickly pears, especially Indian fig (Opuntia ficus-indica). Both the fruits and the prickly pear “pads” (nopales), which technically are flattened succulent stems, are eaten. Drinks prepared from some cactus fruits have been a popular native medicine for fevers. In Mexico, young stems of chollas, resembling string beans, are eaten. In Latin America, species of Opuntia, Cereus, and other genera are planted around houses, often forming a “living fence.”

Polygonaceae

The smartweed or buckwheat family, Polygonaceae, consists of popular vegetables and cultivated ornamentals. The most notable species is buckwheat (Fagopyrum esculentum); its edible seeds are used sometimes in flour, particularly for buckwheat pancakes, and portions of the plant are frequently included in animal feed. The leafstalks of rhubarb (Rheum rhabarbarum) are edible, but the leaf blades are poisonous. Sea grape (Coccoloba uvifera), growing on beaches, produces edible fruit used in making jellies. Ornamental plants include the sea grape; giant knotweed (Fallopia sachalinense); Chinese fleecevine (F. baldschuanica); ribbonbush (Homalocladium platycladum); and Mexican coral vine (Antigonon leptopus). Spotted smartweed, or spotted knotweed (Persicaria maculosa), is a common weed in the United States, but it is grown as an ornamental in many parts of Europe. A number of common weeds and pasture plants belong to this family, such as common sorrel (Rumex acetosa) and sheep’s sorrel (R. acetosella). Notoriously difficult to eradicate, Japanese knotweed (Fallopia japonica) is recognized as one of the worst invasive species in parts of Europe and North America.