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COSEWIC assessment and update status report on the Bluehearts in Canada

COSEWIC Status Report
on the
Buchnera americana
in Canada

Species Information

Name and Classification

Scientific name:
Buchnera americana L.
Common name:
Family name:
Scrophulariaceae (figwort family)
Major plant group:
Angiosperm (dicot flowering plant)

Kartez (1996) treats B. americana as including B. floridana Gand. which is a relatively common entity in the southern United States (North Carolina to Mississippi). Most southern floras and Pennell (1935), however, recognize B. floridana as a distinct species. B. americana has a larger corolla (tube 10-12 mm long, the lobes 5-8 mm long) and prominently 3-veined, lance-ovate leaves (Clewell 1985). B. floridana has corolla lobes less than 5 mm long and lanceolate-elliptic leaves which are obscurely, or not at all, 3-veined (Radford et al. 1968). Vincent (1982) developed the following key to separate the two taxa:

  1. Corolla tubes mostly 10-14 mm long; calyces mostly 6-7 mm long, pubescent throughout with short or long, straight to antrorsely-appressed, simple or minutely callous-based hairs; capsules mostly 6-8 mm long, equalling or slightly longer than calyses; mid-stem leaves mostly ovate-lanceolate, irregularly and coarsely toothed, widest at or below middle…. B. americana

  2. Corolla tubes mostly 6-10 mm long; calyces mostly 4-5(6) mm long, pubescent throughout or only on upper 1/3 with short, crisped, antrorse, callous-based hairs; capsules mostly 4-6(6.5) mm long, longer than calyses; mid-stem leaves mostly oblong to oblanceolate, entire or remotely and finely toothed, widest at or above middle…..B. floridana

The author of this report uses B. americana in the strict sense for purposes of North Americana distribution and status.


Bluehearts is a perennial, ranging in height from 40 to 80 cm. It is a facultative parasite on the roots of a variety of trees. Plants are usually unbranched, have hairy stems and sessile, opposite leaves. A flowering spike of deep purple, stalkless flowers is produced at the top of the plant (Figure 1). In Ontario, flowering begins in mid-July and lasts until early September. Fruits are oblong capsules about 7 mm long. 

Figure 1: Inflorescence of Bluehearts

Figure 1: Inflorescence of bluehearts (photo by Dan Tenaglia, taken at Dorris Creek Prairie Cons. Area,Barton County, Missouri)

Photo by Dan Tenaglia, taken at Dorris Creek Prairie Cons. Area,Barton County, MO.