FLORA OF THE DISTRICT OF COLUMBIA. 259 



6. HOUSTONIA L. 



Stems glabrous, very slender; flowers solitary on long slender pedicels; plants spread- 

 ing by threadlike rootstocks, often forming dense mats 1. H. coerulea. 



Stems finely hairy or long-hairy, stout; flowers in cymes; plants tufted, never with 

 threadlike rootstocks. 

 Stems minutely hairy; stem leaves linear-oblong or linear-lanceolate; capsules as 



high as broad or higher 2. H. longifolia. 



Stems soft-hairy; stem leaves broadly ovate to ovate-oblong or lance-ovate; cap- 

 sules broader than high 3. H. purpurea. 



1. Houstonia coerulea L. Bluets. 

 Open fields or meadows; common. Apr .-May. Eastern N. Amer. 



The flowers are shown in plate 41 A. 



2. Houstonia longifolia Gaertn. 



Woods along the Potomac above Washington; frequent. July-Sept. Eastern 

 U. S. (E. purpurea longifolia A. Gray.) 



3. Houstonia purpurea L. 



Woods and fields; common. May-Aug. Eastern U. S. 



145. CAPRIFOLIACEAE. Honeysuckle Family. 



The weigelas, Diervilla rosea, D. japonica, and other species, are handsome ornamen- 

 tal shrubs grown in parks and gardens. Species of Abelia also are cultivated. Dier- 

 villa lonicera Mill was collected along Rock Creek (Oliver) many years ago. 



Plants herbaceous. Flowers yellowish, greenish, or purplish, borne in the axils of 



the leaves 3. TEIOSTETJM. 



Plants woody. 

 Corolla distinctly long-tubular; vines. Flowers red, or white or pink changing to 



yellow 1 • LONICEEA. 



Corolla not long-tubular; erect shrubs or rarely trees. 



Leaves pinnate. Flowers white, in large flat cymes 6. SAMBTJCUS. 



Leaves simple. 

 Flowers mostly clustered in the axils of the leaves, white or pinkish . 



2. SYMPHORICARPOS. 

 Flowers in large flat terminal cymes, white 4. VIBURNUM. 



1. LONICERA L. Honeysuckle. 



A common cultivated bush honeysuckle is L. tatarica L. It has pink or white 

 flowers, and red fruits in June. 



Upper leaves united by their bases around the stem; flowers in terminal spikes, red; 



fruit red 1- I*- sempervirens. 



Upper leaves distinct; flowers in pairs in the upper axils, white or pink, turning 



yellow; fruit black 2. L. japonica. 



1. Lonicera sempervirens L. Trumpet honeysuckle. 



Occasional in thickets and along fences. May-June; fr. June-July. Eastern U. S. 

 B. Lonicera japonica Thunb. Japanese honeysuckle. 



Abundant almost everywhere. May-Oct.; fr. Sept.-Feb. Naturalized from Asia. 



The flowers are shown in plate 42. 



2. SYMPHORICARPOS Ludw. 



Style glabrous; fruit white 1- S. albus. 



Style hairy; fruit red 2. S. orbiculatus 



