The tamarisk family consists of about 4 or 5 genera of shrubs and trees from Eurasia and Africa. Species are commonly halophytes, occurring in saline or alkaline habitats. Twig Much branched, often green and photosynthetic. leaf Commonly small and scalelike. Flower Usually tiny, often in branched inflorescences; sepals, petals, and stamens each commonly 4 or 5; ovary superior, 1-chambered, with usually 3 styles. Fruit Capsule containing hairy seeds.
TAMARIX: tamarisks or Saltcedars
Of the approximately 55 species of tamarisk native to the Old World (Eurasia and Africa), about 9 have been introduced to North America, and at least 2 have become aggressively invasive. Shrubs and trees with a fine, wispy, often drooping terminal stem that are grayish-green, photosynthetic, and mostly deciduous at the end of a season. Bark Brownish or reddish-brown, smooth at first, eventually becoming grayish brown and furrowed. The leaf is Reduced to tiny scales that have salt-excreting glands and thus are sometimes encrusted with white. Flower Tiny, whitish to pinkish, usually bisexual (when unisexual, male and female on the separate plant), borne in racemes that are either single or in branched clusters. Sepals 4 or 5, separate or joined at the base; petals 4 or 5, separate; stamens 4 or 5, attached to the edge of a central nectar disk with 4 or 5 lobes, or immediately beneath it. Fruit Tiny capsule splitting into 3 or 4 segments, with many tiny seeds, each seed with a tuft of hairs at the tip, resembling a minute whisk broom.
The biblical manna may have come from the excrescence of insects feeding on tamarisk. Honey producers make dark, flavorful honey from the flowers. Tamarisk was apparently introduced to the U.S. in the 1850s for ornamental use, for windbreaks, or to stabilize erosion. It raced across the West as an invasive plant in the early The 1900s, displacing native vegetation along watercourses, overtaking more than half a million hectares. The Northern Tamarisk Beetle (Diorhabda carinulata) and closely related species are now being used for biological control. Tamarisk is deep-rooted, tapping water that other plants may not be able to access, but also has widely spreading roots, which give rise to new plants. The tiny seeds float upon the wind for long distances. Other means of eradication are expensive, requiring chemical and/or mechanical means, and sometimes also the burning of dense stands.
In North America, tamarisks (or saltcedars)occur in places that are wet at least part of the year, such as saline plains, floodplains, roadsides, riverbanks, canyon bottoms, and springs, from low to moderate elevations, in much of the w. and se. U.S. The slender green terminal, often drooping twigs with tiny alternate, scale-like leaves are diagnostic, especially when examined in combination with inflorescences of minute pinkish-white flowers. At first glance, Casuarina, which has not been naturalized in the West, is very similar, but it has scale-like leaves in rings, making a jointed stem, and a small avoid, rough woody fruiting body.
Tamarix species are differentiated by small differences of the flower, particularly the shape of the nectar disk and attachment of stamens to the nectar disk. Also important is the presence or absence of minute teeth on leaves or sepals, though species are practically impossible to identify without flowers. Flower and leaf features require at least a 10×lens to see. To confound the problem, species will hybridize when in contact with one another, and a number of floral parts may vary on any one plant.
Still, with a lens and persistence, one can usually identify a species, or an intergrade between species. Look at the number of stamens per flower (4 or 5) and the junction of the stamens with the nectar disk in the center of the flower. In this treatment, the first species, T. parviflora, has 4 stamens. The second group of species, beginning here with T. gallica has 5 stamens with flared bases of filaments confluent with the nectar disk, and no well-defined disk lobes between the filament bases. The third group of species, headed by T. chinensis, has 5 stamens with slender filaments, and an abrupt junction between the nectar disk and narrow base of the filament, the disk with well-defined lobes between the filament bases.
