Agrimonia

The outer rim of the floral tube (“calyx tube”) bears 2 or more rows of hooked bristles, which elongate and stiffen in fruit, closely resembling the beaks on achenes of Geum. In Agrimonia, however, it is the entire floral tube that breaks free from the plant, the 2 achenes enclosed, and is well adapted for animal dispersal. The floral tube is usually top-shaped and ± grooved and furrowed.

1. Principal leaflets (excluding tiny intermediate ones) (11–) 13–17, narrowly elliptic (mostly ca. 3–4 times as long as wide); axis of inflorescence with glands largely obscured by ± dense short hairs (besides scattered long hairs).

A. parviflora

1. Principal leaflets 5–9 (–11), narrowly to broadly elliptic or slightly obovate (but usually 1.5–2 (–3) times as long as wide); axis of inflorescence with glands conspicuous, obscured, or absent.

2. Axis of inflorescence conspicuously glandular; grooves of floral tube without appressed hairs; bristles of floral tube in common species widely spreading or reflexed (except for inner ones).

3. Bristles of calyx tube elongating to as much as 3.5 (–4) mm, the outer ones widely spreading to reflexed; axis of inflorescence with conspicuous widely spreading scattered long hairs; sepals ca. 2–2.7 (–3) mm long; fruiting floral tube ± top-shaped, often conspicuously grooved, ca. 3–4.5 mm wide (excluding bristles); common throughout Michigan.

A. gryposepala

3. Bristles of floral tube elongating at most to 2 mm, ascending or slightly spreading; axis of inflorescence with very few if any long hairs; sepals (calyx lobes) ca. 1.5–1.8 mm long; fruiting floral tube ± hemispherical with rounded sides, slightly if at all grooved, ca. 2–2.5 mm wide; very rare, in southern Lower Peninsula.

A. rostellata

2. Axis of inflorescence without glands, or these sparse and ± hidden by pubescence; grooves of floral tube with a strip of white appressed hairs (strigose); bristles of floral tube ± strongly ascending or erect.

4. Lower surface of leaflets velvety to the touch, the hairs ± strongly spreading; stipules of mid-cauline leaves ovate-reniform, ± coarsely but regularly toothed; southern half of the Lower Peninsula.

A. pubescens

4. Lower surface of leaflets smooth or scabrous to the touch, the hairs usually ± appressed; stipules of mid-cauline leaves mostly with a prolonged lanceolate terminal tooth or lobe; Upper Peninsula and northernmost Lower Peninsula.

A. striata

All species found in Agrimonia

Agrimonia gryposepalaTALL AGRIMONY 
Agrimonia parvifloraSWAMP AGRIMONY 
Agrimonia pubescensSOFT AGRIMONY 
Agrimonia rostellataBEAKED AGRIMONY 
Agrimonia striataROADSIDE AGRIMONY 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. July 25, 2017. http://michiganflora.net/genus.aspx?id=Agrimonia.