VERBENA FAMILY (VERBENACEAE) 



A. Leaves simple. 



Key to the 6 species illustrated (Nos. 225-230) 



Leaves less than 6 inches long. 

 C. Leaves lance-shaped or narrowly elliptic, 2-414 inches long, lower surface gray green, hairy ; trees of 

 mangrove swamp forest — 22.5. Avicennia nitida. 

 CC. Leaves elliptic ; upland trees. 



D. Petioles short, less than 1 inch long; leaf blades hairless or nearly so, the upper surface slightly 

 shiny. 

 E. Leaves with few side veins ; flowers with definite stalks — 226. Citharexylum caudatum. 

 EE. Leaves with prominent network of small veins when dry, turning red before falling, petiole 

 pink or orange; flowers almost stalkless — 227. Citharexylum fruticosum. 

 DD. Petioles long, l-2i,l> inches long; leaf blades rough, lower surface pale yellow green, with minute 

 scales and hairs and prominent veins — 228. Petitia domingensis. 

 BB. Leaves very large, elliptic, 12-15 inches or more in length, thickened, leathery, and harsh, the upper surface 

 rough, the lower surface soft hairy — 229. Tcctona grandis* 

 AA. Leaves mostly compound with 3 elliptic leaflets, often only 1 or sometimes 2, the end one largest — 230. Vitex 

 divaricata. 



225. Mangle prieto, black-mangrove 



This is 1 of the 4 kinds of mangrove trees which 

 form swamp forests at sea level in salt water and 

 l)rackish water along silty seashores. Mangle 

 prieto is distinguished by: (1) opposite lance- 

 shaped or narrowly elliptic leathery leaves 2-4:1^ 

 inches long and i/^-l% inches broad, the upper 

 surface yellow green and often shiny, the lower 

 surface gray green with a coat of fine hairs giving 

 a grayish color to the crown, and both surfaces 

 often with scattered salt crystals and salty to the 

 taste; (2) clusters of several crowded stalkless 

 white 4-lobed flowers about i/^ iri^h long ^rid % 

 inch across; (3) elliptic flattened blunt-pointed 

 seed capsules I-I14 inches long and about % inch 

 wide, yellow green and finely hairy, often split- 

 ting open into 2 parts; and (-4) bright orange to 

 yellow inner bark. 



Commonly a small tree or shrub 10-40 feet high 

 and attaining a trunk diameter of 1 foot in Puerto 

 Rico, evergreen with rounded crown of spreading 

 branches, liark is smooth and dark gray or brown 

 on small trunks but becomes dark brown, fissured 

 and scaly, and thick. The inner bark, brown 

 deeper within, has a slight salty taste. Twigs are 

 gray or brown, finely hairy when young, with en- 

 larged and ringed joints or nodes. 



Often numerous fleshy pencillike projections 

 (pneumatophores) rise vertically from the long 

 horizontal roots in the mud under a tree, perhaps 

 aiding in bringing air to the roots. Masses of 

 roots 1/^-11/2 feet long sometimes hang in the air 

 from the upper part of large trunks. 



The short petioles are Vs-Vz ii^*^li long- Blades 

 are sihort-pointed or blunt at apex, short-pointed 

 at base, and not toothed on edges. 



Flower clusters (spikes or panicles) are terminal 

 and lateral, erect on 4-angled stalks i/^-lV^ inches 

 long, and bear several finely hairy flowers. The 

 gray-green calyx is cup-shaped, Yiq inch long, 

 deeply 5-lobed, with 3 smaller scales (bracts) out- 

 side; the corolla tube about the same length has 

 4 slightly unequal spreading rounded or notched 

 lobes, white but yellowish at base; 4 stamens %q 

 inch long are inserted on corolla tube near base; 



Avicennia nitida Jacq. 



and the pistil %6 inch long has a 1-celled ovary, 

 slender style, and 2-lobed stigma. 



The fleshy seed capsule contains 1 large dark 

 green seed which is an embryo plant without 

 seedcoat. Often the seed germinates on the tree, 

 splitting open the fruit. Upon falling, the young 

 plant continues growth in the mud or may float 

 and be transported by tide and currents. Flower- 

 ing and fruiting nearly throughout the year. 



The sapwood is light brown and thick. The 

 iieartwood is dark brown or blackish. The wood 

 is very hard, very heavy (specific gravity 0.9), 

 and strong. It has a coarse, uneven, interlocked 

 grain and prominent growth rings and is very sus- 

 ceptible to attack by dry-wood termites. 



Seldom sawed into lumber, the wood is used 

 primarily for posts in Puerto Rico. Timbers of 

 larger size have been employed elsewhere for vari- 

 ous purposes, such as piers, wharves, and other 

 marine construction, as well as for telegraph and 

 power poles and crossties. The wood is used also 

 for fuel and charcoal, and the bark for tanning. 



This is an important honey plant of coastal 

 areas, producing clear white honey of high quality. 

 The flowers are rich in nectar and attract bees. It 

 is reported that the sprouting seeds are edible 

 when cooked but poisonous raw. Salt for cooking 

 or eating purposes can be obtained from the salt- 

 coated foliage. 



This species seems more hardy than the other 3 

 kinds of mangroves, to which it is not related. It 

 penetrates farther inland along rivers and in the 

 United States ranges farther northward, beyond 

 the tropical zone. In Puerto Rico it appears to 

 withstand prolonged flooding better than white- 

 mangrove (Laguncularia racemosa). The ad- 

 vancing thickets of mangroves with networks of 

 roots collect and hold silt, thus building up the 

 shores. 



In mangrove forests in brackish water near pro- 

 tected silty shores and at mouths of rivers around 

 Puerto Rico, usually with other species of man- 

 grove but rarely forming pure stands. Also Cule- 



476 



