Pyrola americana (P. rotundifolia) round-leaf Pyrola Pyrolaceae PYAM; Bx, pb (Z. Wang 2017); Q, f; R, ah, ap (E. Danielsen 4/2017), bd, gb, h, jw, k, lt, ro, sv, t, wp;



Pyrola.rotundifolia.M.B. Gargiullo ca. 2009

Pyrola americana is a low perennial herb, basal rosette, evergreen, colonial from rhizomes, but slow-growing, roots associated with specialized mycorrhizal fungi. 

Leaves all basal, 2.5-7 cm long, tip rounded, base extending down leaf stalk, veins pale, depressed above, underside and petiole often reddish (leaves of the closely related P. elliptica live 54 weeks (Hicks and Chabot 1985). 

Flowers white, radially symmetrical, 5-parted, to 2 cm wide, hypogynous, petals overlapping, tips rounded, sepals much shorter than petals; stamens 10; ovary 5-parted, style elongate and persistent in fruit; inflorescence a raceme on a stalk 15-30 cm tall; blooming July- Aug. 

Fruit a capsule, becoming dry and splitting open from the base to release many minute seeds; wind dispersed during late autumn and winter. 

Wetland status: FAC. 

Frequency in NYC: Occasional. 

Origin: Native. 

Habitat: Moist to dry, undisturbed forest understory, usually in sandy, acid soil of oak forests; shade tolerant. Found in forest soil pH 4.8-5.4 (Gargiullo unpublished data). 

Notes: Plants eaten by Ruffed grouse (Martin et al. 1951). The closely related P. elliptica requires at least 0.4% sunlight in order to survive (compensation point), cannot use more than 7.0% full sunlight (saturation point) (Hicks and Chabot 1985). Seeds of Pyrola are very difficult to germinate and grow. One study of Pyrola seeds in sterile culture found that germinated seeds produced colorless, branched structures that developed for over three years without further differentiation. Up to four fungi have been isolated from the mycorrhizas of Pyrola including a basidiomycete. Mycorrhizas of Pyrolaceae seem to resemble those of Ericaceae (Smith and Read 1997). In general, plants in the family Pyrolaceae are very difficult to either grow or transplant because of their very specialized mycorrhizal associations and possibly other ecological needs.