1. Tamarix ramosissima Ledeb. (salt cedar)

Pl. 567 g–i; Map 2655

Plants shrubs or small trees to 5 m tall, highly branched, deciduous and often shedding branchlets in autumn. Bark reddish brown to dark purplish gray, smooth or becoming ridged with age. Twigs slender, light green, glabrous. Leaves alternate, sessile. Stipules absent. Leaf blades 0.8–1.5 mm long, scalelike, glabrous, light green, lanceolate to ovate, the base clasping the stem, the tip sharply pointed, the margins entire. Inflorescences panicles with racemose branches (rarely reduced to simple racemes) of numerous tiny flowers. Flowers perfect, actinomorphic, hypogynous, short-stalked, each subtended by a minute scalelike bract, the perianth persisting in fruit. Sepals 5, 0.5–1.0 mm long, lanceolate to elliptic or ovate, bluntly to sharply pointed at the tip (rarely rounded), light green, the margins irregularly and minutely toothed, often thinner and white. Petals 5, 1.0–1.8 mm long, obovate to oblong-obovate, light pink to pink, fading to grayish white. Stamens 5, exserted. the filaments attached between the shallow lobes of a nectar disc. Pistil 1 per flower, of 3(–5) fused carpels. Ovary superior, flask-shaped, with 1 locule, the placentation appearing more or less basal. Styles 3(–5), usually appearing twisted, each with 1 club-shaped stigma. Ovules numerous. Fruits capsules, 3–4 mm long, tapered to a beaklike tip, dehiscing longitudinally into 3(–5) valves. Seeds 0.5–0.7 mm long, the body minute, obovoid, yellowish tan, with a slender tail-like appendage at the tip, this with a coma of dense long fine hairs that spreading at right angles to the axis when dry. 2n=24. April–September.

Introduced, uncommon, mostly in the Big Rivers Division, but occasionally escaped from cultivation elsewhere in the state (native of Europe and Asia, widely naturalized in the southeastern U.S., more sporadically in the central and southeastern U.S.). Sand and gravel bars along rivers; also mine spoils, roadsides, alleys, and railroads.

Of the 54 species of Tamarix, 10 have been introduced in the United States (Crins, 1989). They were originally cultivated as ornamentals, for wind screens, and to a lesser extent for mine spoil reclamation, and most subsequently escaped. Especially in the arid southwestern states, a few of these species, including T. chinensis Lour., T. ramosissima, and their naturally occurring hybrid have become extremely bad invasive weeds in floodplain habitats (Gaskin and Schaal, 2002), where they crowd out native riparian plant communities and, by virtue of their extensive root systems and high water use, drastically lower the water table. Nearly all of the species thrive in salty soils and the genus is characterized by glands that secrete salts taken up by the roots and translocated. The plants usually have minute white beadlike salt secretions on the surfaces of the branches, leaves, and calyces.

Steyermark (1963) appears to have used a very preliminary account of the genus in the southwestern United States by Shinners (1957), which included only five species, as the basis for his acceptance of T. gallica L. (French tamarisk) in Missouri. Baum (1967) presented the first comprehensive account of the naturalized tamarisks, but curiously included only T. parviflora DC. (small-flowered tamarisk) for Missouri (later erroneously accepted by Yatskievych and Turner [1990]). Tamarix parviflora has 4-parted flowers, whereas all of the fertile specimens from Missouri examined thus far are clearly 5-merous and key to T. ramosissima in Baum’s (1967, 1978) keys. Crins (1989) and others have questioned whether T. ramosissima is distinct from T. chinensis, which differs only in subtle characters of the sepal shape and attachment points of the stamens on the nectar disc. However, Gaskin and Schaal (2002, 2003) presented molecular evidence that the two should be treated as closely related but separate species. Baum himself suggested that further studies were desirable in regions where these two taxa grow together. It should be noted that most tamarisk species are indistinguishable if no flowers or fruits are present.