FLORA OF THE DISTRICT OF COLUMBIA. 235 



2. Cuscuta polygonorum Engelm. Smartweed dodder. 

 On various herbs in damp situations, particularly Persicaria lapathifolia and P. 



pennsylvanica; abundant on these species on the Potomac flats; has been found on 

 red clover growing near infested Persicaria. June-Sept. Widely distributed in N. 

 Amer. (C chlorocarpa Engelm.) 



3. Cuscuta coryli Engelm. Hazel dodder. 

 North of Glen Echo park, Oct. 16, 1904 {Mrs. F. H. Eillman). Eastern U. S. 



4. Cuscuta gronovii Willd. 



Common in moist places, often forming dense yellow areas on low wet ground. 

 July-Aug. Widely distributed in the U. S.; occurring on many herbaceous plants 

 and small shrubs. 

 6. Cuscuta compacta Juss. 



Common on low shrubs in woods and along streams. July-Sept. Eastern TJ. S. 



131. POLEMONIACEAE. Phlox Family. 



Leaves alternate, pinnate 1. POLEMONITJM. 



Leaves opposite or fascicled, simple, entire 2. PHLOX. 



1. POLEMONITJM L. Jacob's-ladder. 



1. Polemonium reptans L. 



Rich soil in ravines of the upper Potomac; Rock Creek Park; Woodside; Ken- 

 sington; infrequent. Apr.-May. Eastern U. S. 



2. PHLOX L. 



Leaves awl-shaped, rigid, crowded; stems creeping, more or less matted, woody at 

 base 1 . P. subulata. 



Leaves flat, opposite; stems erect or ascending, herbaceous. 

 Inflorescence a many-flowered panicle; stem leaves 5-10 cm. long. 

 Panicle pyramidal; leaves often 3 cm. broad; calyx lobes awn-pointed. 



2. P. paniculata. 

 Panicle narrowly oblong or ellipsoid; leaves not much. over 1.5 cm. broad; calyx 



lobes lanceolate, not awn-pointed 3. P. maculata. 



Inflorescence a few-flowered cyme; leaves 3-6 cm. long. 

 Upper leaves lance-ovate or oblong-lanceolate; stems decumbent at base, with 



sterile leafy shoots 4. P. divaricata. 



Upper leaves linear or linear-lanceolate; stems erect or nearly so, with no decum- 

 bent sterile shoots 5. P. pilosa. 



1. Phlox subulata L. Moss pink. Ground pink. 

 On rocks at Great Falls and Broadwater. Feb.-May; fr. June. Eastern U. S. 



2. Phlox paniculata L. Garden phlox. 

 Frequent in moist soil along the Potomac and occasional elsewhere. July-Aug.; 



fr. Oct. Eastern U. S. 



The perennial garden phlox is derived from this species, and escapes often persist 

 for years. 



3. Phlox maculata L. Wild sweet william. 

 Occasional in moist woodland along streams; near Laurel and Riverdale; more 



common in Va. July-Aug.; sometimes earlier. Eastern U. S. 



4. Phlox divaricata L. Blue phlox. 

 Frequent in moist woods and thickets along the Potomac and its tributaries. Apr. - 



May; fr. June. Eastern N. Amer. 



Flowering plants are shown in plate 18 A. 



