H. drummondii seedling shown in photo below, scale is 5 mm

Hedeoma drummondii Seedlings, 11 March 2014

by Bob Harms 

The literature discussing the Hedeoma drummondii complex mentions ontogenetic variation in leaf morphology, but it is never clear whether the statements are in reference to seasonal dimorphism or plant development; e.g., R.S. Irving 1968 mentions ‘juvenile’ forms, indicating:

Winter leaf form & pubescence is seasonal and not a juvenal form (i.e., seasonal dimorphism as opposed to heteroblasty), as can be seen from the images of both below. The seedlings shown here germinated in early January 2014 and have developed despite nighttime temperatures commonly around 20°F.

3 seedlings and branch with winter leaves (darker, on left)	winter leaves (left) & 2 seedlings (right), from photo on left

Shown below are a cotyledon and first true leaves on the above seedling. The first true leaves appear to be glabrate, in contrast with (a) later leaves and (b) winter leaves. They already have well developed glands. The purple stem and lower lamina color is typical of all Hedeoma winter leaves, both juvenal and seasonal.

Cotyledon	First true leaves

In form the leaves quickly narrow from broadly ovate to elliptic–oblong.

apex leaves