Introduction

     The crape myrtle (Lagerstroemia sp.), native to SE Asia, is a widely popular woody ornamental flowering shrub/small tree throughout southeastern US landscapes. The wide assortment of inflorescence colors, forms and sizes, coupled with a rather long flowering period (up to 120 days), plus a commonly found exfoliating bark, have given rise to the popularity of this genus. Breeding programs in USA and Europe have generated, in the last three decades, a wide range of plant sizes (from miniature 30 cm shrubs to +10 m tall trees), growth habits (broad, upright, weeping, etc..), cold hardiness (Zones 6-10), disease resistance (powdery mildew) and a wide range of bark characteristics, flower color and foliage fall colorations. Likely unknown to gardeners and horticulturists are the commercial timber and medicinal uses of some of the approximately eighty (80) species found in the Lagerstroemia genus.

     The widespread use and popularity of Lagerstroemia has has led to its categorization as a ‘naturalized’ U.S. plant, and this status is crowned with its recent designation as the Official Shrub for the State of Texas (Resolution 14, 75th State Legislature, 1997).

 Botanical and Horticultural Description

     Out of all the Lagerstroemia species, L. indica, and L. speciosa are the most widely know and cultivated. L. indica or the common crape myrtle is generally described as a multi-trunk medium to large shrub or tree that often does not exceed an 8 to 10 m height. The trunks or stems are smooth, fluted, pale to pinkish-brown color with peeling bark. The deciduous simple leaves are undivided, mostly opposite or whorled with the upper leaves sometimes alternate. The glabrous leaves are subsessile (very short petiole), and have generally pointed, elliptic or obovate to oblong blades 2.5 to 6 cm long, broad-cuneate or rounded at base. Leaf fall color can have a range of yellow, orange, and red color hues. The most distinctive feature for these plants is their long (10 to 40 cm) and terminal or axillary panicles with ruffled flowers in various shades of red, pink, white, lavender and purple colors. The symmetrical flowers range in size from 2 to 5 cm, have top-shaded to hemispherical, often ribbed or winged calyxes with six to nine segments. The petals, commonly six, have broad, fringed or crinkled blades with their lower portions narrowed into long, slender shafts or claws. There are many (about 40) long-stalked stamens and a long style tipped with a head-like stigma.  The dry fruit are six-parted, globose, brown capsules (1 to 1.5 cm in diameter) that contain seeds winged at their tops.

L. speciosa, commonly known as Queen’s or giant crape myrtle, can reach 20 to 30 m heights. The trunks, highly valued as timber, are light colored and have a scaling bark. The leathery, simple, glabrous leaves are pointed-elliptic to ovate, 10 to 30 cm long by 5 to 13 cm wide. The 4 to 7 cm diameter flowers, arranged in loose panicles 40 to 60 cm long, have twelve-ribbed, bell-shaped calyxes with six or occasionally seven lobes or teeth. The corollas have six crinkled, crape-like, pink, mauve or purple petals, and the flower centers are crowded with as many as 100 yellow stamens.  The fruits are 2 to 3 cm in diameter. The origin of L. speciosa (native to India) makes it much less hardy than L. indica, and thus limits its cultivation to tropical and subtropical regions, like southern Florida and California, and Hawaii in the U.S.

The rather obscure and perhaps nearly extinct L. fauriei, found only in the island of Yakushima, Japan has brought the most significant developments in the breeding of modern ornamental Lagerstroemia cultivars, contributing mainly with powdery mildew resistance, cold hardiness and handsome bark. This tree commonly exceeds a 10 m height, with beautiful, exfoliating, dark red-brown bark in its stems. The simple, long (up to 10 cm) and narrow (4 cm or less), oblong to ovate, leathery leaves have sinuate margins and attenuated tips with eight to thirteen pairs of lateral veins. Their undersurfaces have tufts of hair in the axils of the veins. The white flowers are borne in small (5 to 10 cm long) and dense terminal panicles.

 Lagerstroemia indica (Common Crape Myrtle) identification key

Leaves: Simple, 1-3 inches long (2.5 to 7.5 cm); arrangement is opposite or in whorls of three; upper leaves may be alternate; color is cultivar dependant but generally a lustrous dark green above and paler below. The leaves have very short petioles (stalks) and usually have pointed, elliptic to oblong blades with rounded bases. Fall (autumn) leaf color within a plant is varied, including yellow, orange and red-colored leaves.

Flowers: Symmetrical, 1-2" (2.5-5 cm) and in five basic colors: red, pink, white, lavender or purple; some cultivars have bicolor (picotee) flowers (i.e. pink petals with white borders). The individual flowers are arranged in terminal or axillary panicles (inflorescences or clusters) 6-12" long (15-30 cm). Panicles appear from late May to late September and length of blooming is cultivar dependent. The individual flowers generally have 6 crinkled (fringed, ruffled) petals; calyxes are often ribbed or winged with six to nine segments. The lower portions of the petals are narrowed into long, slender shafts or claws. There are about forty long-stalked stamens and a long style tipped with a head-like stigma.

Fruit: Brown-colored, broad-ellipsoidal dehiscent capsules with 6 parts (valves), arranged in upright spikes. Individual capsules are 0.5 inch (1.2 cm) in diameter and contain ~0.4 inch (1 cm)-long winged seeds. Fruit spikes persist through the winter.

Twigs: Slender and angled (almost squarish) with prominent wings; glabrous; initially red- or green-colored, they turn brown as they mature; buds very small.

Trunks and Bark: Smooth, sinewy, fluted, pale pinkish-brown trunks. The smooth, grey to brown color bark is exfoliating (peeling) and exposes under-bark colored in shades of cinnamon brown, reddish brown and green. Some cultivars have very attractive (outstanding) bark.

Form and Habit: Usually medium (10 ft.; 3 m) to large shrub or a small multi-stemmed tree (up to 40 ft.; 12 m). There are some relatively recent dwarf and miniature cultivars (18' to 5 ft.; 45 cm to 1.5 m). Naturally or culturally grown as a multi-trunked shrub or small tree. There is a variety of plant forms: vase, upright, globose, broad and weeping (mostly dwarf and miniature cultivars).