H. reverchonii var. serpyllifolia in early morning light, Hays Co.

Leaf & Flower Color as Differentiae in the Hedeoma drummondii Complex
by Bob Harms  email-here

The key in Diggs et al. 1999, Illustrated flora of North Central Texas (BRIT, p. 758) gives color distinctions for the H. drummondii complex, repeating R.S. Irving's 1980 features but adds corolla color. So far as I can determine color, even leaf color, does not distinguish these taxa. Neither fresh materials nor dried specimens support color as a reliable characteristic.

The following table gives the colors from Diggs et al.

Leaf Color Corolla Color
H. drummondii bright green blue
H. reverchonii var. reverchonii gray green white or
H. reverchonii var. serpyllifolia dark green

Although online photos as well as my own show a wide range of colors for all three taxa, with rare exceptions the corolla color is a shade of lavender (lavender-purple to light pink-lavender). Blue flowered H. drummondii may exist, but I would need to see it in the field or see a photo in full sun to convince me (since lavender tends to photograph blue in shade). I have not seen white corollas, but in strong sunlight the pale lavender often appears to be white.

The following 3 photos illustrate less common colors, in part due to lighting conditions. The center image is in the shade. The rightmost image was taken in early morning, and might appear white in bright sun. Place the cursor over an image to get the ID; click for enlargement.

The images below with more 'normal' color illustrate the difficulty in using color.

With fresh materials, photos or scans [determinations based on scent, leaf form, calyx teeth]:

[click for large image]
H. drummondii H. reverchonii var. serpyllifolia H. drummondii H. r. var. serpyllifolia H. r. var. reverchonii
Hays Co., May 12, 2012 Travis Co., May 12, 2012

With TEX/LL herbarium collections [determinations by Irving]:

[click for large image]
H. drummondii, Travis Co.

H. reverchonii var. serpyllifolia, Travis Co.

H. reverchonii var. reverchonii, Travis Co.

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