Chaptalia texana Type III: Closed, Nodding Head; No Apparent Ligules
by Bob Harms  email-here

In a small valley on Purola Preserve with a creek that enters Deadman's Creek all plants examined were of Type III, easily recognized by the lack of apparent ligulate flowers. Initially I had concluded, even after preliminary microscope inspection of the florets within the pappus, that this type lacked ligulate flowers (and was thus bimorphic).

Dense pappus bristles surround the corolla and style.

But when a head's pappus bristles had dried and expanded, and — importantly — the tiny ligules had turned purple, I reexamined the florets and discovered that this group possessed vestigial ligules, approximately 2 mm long & 0.23 mm wide, with a tip c. 1–2 mm below the style branches. Shown in the dissected florets below.

Counts of all florets from type III heads at different locaations showed:

  count 1 count 2 count 3 averages for 3 counts
of type III heads
reduced ligulate, pistillate 16 15 22 18
eligulate, pistillate 40 40 38 39
central perfect 12 12 13 12
total: 68 67 73 69

The mouth of the tightly closed involucre at anthesis is shown below. The style branches visible only at the very periphery, against the phyllaries, [red box] are from the hightly reduced ligulate florets. The perfect central florets, with style branches exerted, are within the yellow area. The styles of the eligulate pistillate florets in between are largely concealed by the pappus, although a few pink tips are visible.

As a head develops the achene beaks elongate, pushing the florets and pappus out from the involucre. The follwing image illustrates 5 stages in this process. [Click on a head to view enlargement of that head.]

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