FLOE A OF THE DISTRICT OF COLUMBIA. 257 



3. Plantago virginica L. 



Open fields; common. Apr .-May. Eastern U. S. to Mex. 



4. Plantago lanceolata L. English plantain. 

 Fields and waste ground; abundant. May-Aug. Native of Eur. and Asia; natu- 

 ralized nearly throughout the U. S. and southern Can. 



Known also as rib-grass. 



6. Plantago cordata Lam. Heart-leap plantain. 



Sandy shores at and opposite Alexandria, often growing in water; Eastern Branch. 

 May-Aug. Eastern U. S. 



6. Plantago major L. Common plantain. 

 Moist soil; abundant. June-Sept. Eur. and N. Amer.; probably naturalized 



from Eur. in eastern N. Amer. 



7. Plantago rugelii Decaisne. 



Moist ground; common. June-Sept. Nearly throughout the U. S. and southern 

 Can. 



144. RUBIACEAE. Madder Family. 



Plants shrubby; flowers in very dense spheric heads 1. CEPHALANTHTJS. 



Plants herbaceous; flowers never in spheric heads. 

 Leaves apparently in whorls of 4 or more. Corolla wheel-shaped, white, yellow, or 



greenish; calyx lobes obsolete 2. GALIFM. 



Leaves opposite by 2's. 

 Fruit a bright red fleshy berry (rarely white) ; stems slender and creeping, rooting 

 at the joints; leaves evergreen, long-petioled, the blades nearly or quite as 



broad as long. Corolla white 3. MITCHELLA. 



Fruit a dry capsule; stems erect, or sometimes procumbent but not rooting at the 

 joints; leaves not evergreen, the blades usually much longer than broad. 

 Flowers sessile in the axils of the leaves; stipules fringed with bristles. Leaves 



sessile, linear or narrowly lanceolate; plants annual 4. DIODIA. 



Flowers pediceled; stipules without bristles. 

 Corolla white; calyx lobes broadly ovate or oval; flowers mostly in dense 



clusters in the axils of the leaves 5. OLDENLANDIA. 



Corolla bluish purple, pink, or rarely (abnormally) white; calyx lobes linear or 

 lanceolate; flowers solitary on long slender pedicels or in terminal cymes. 



6. HOUSTONIA. 

 1. CEPHALANTHTJS L. 



1. Cephalanthus occidentalis L. Buttonbush. 



Wet ground and along streams; frequent. June-Aug. Eastern N. Amer. 



In some places within our range this is a small tree with well-developed trunk. 



Sherardia arvensis L., field madder, was collected in the Soldiers' Home grounds, 

 June, 1912 {Titus TJlke). Native of Eur.; locally adventive in the U. S. 



Asperula arvensis L. was collected in waste ground along the river front, Washington, 

 May, 1898 (Steele). Native of Eur. ; rarely adventive in the U. S. 



2. GALIUM L. Bedstraw. 



Fruit covered with straight or hooked hairs. 



Leaves in whorls of 6 or 8, bristle-pointed, 1-nerved. 

 Plants annual; stems bristly-hairy on the angles, the hairs turned downward; 



leaves linear-oblanceolate to linear 1. G. aparine. 



Plants perennial; stems glabrous; leaves elliptic or elliptic-oblanceolate. 



2. G. triflorum. 



69289—19 ^17 



