Chaptalia texana Reduced Ligulate Floretss
by Bob Harms  email-here

In an attempt to support my hunch that the florets with reduced ligules correspond to those with visible styles immediately adjacent to the phyllaries, phyllaries were removed from a relatively advanced head.

Five florets from the edge were removed. Then each was searched for the corolla and style from within the surrounding pappus, which was essentially the same color. [Note that the darkened styles seen in the above image were not at the very periphery.]

Floret 1: reduced ligule. The white box is 2 mm long; the flat blade has been moved away from the style in the lower detail.

Floret 2: reduced ligule as a sheath. The detail shows both adaxial and abaxial views showing a c. 1.3 mm grove in the corolla tube (discernable between the yellow dots). Unlike the corolla tube with eligulate florets, the sheath has begun to turn purple and its tip is less than 2 mm from the style branches. (The white box is 2 mm long.)

Floret 3: eligulate. Unlike the reduced ligulate forms, the diameter of the corolla tube is just enough to contain the style; and the tube is much shorter (c. 4 mm long), terminating c. 5 mm below the style branches.

The two other florets were similar to the sheath-ligulate floret 2. Not all florets adjacent to the phyllaries are ligulate (1 of the 5 examined was eligulate). Examination of the receptacle (shown below) showed that the head had 73 florets, 28 at the outer edge (red dots below). Eighty percent of these would mean 22 ligulate florets. The receptacle depressions for 13 central florets were somewhat larger (green dots below); these were assumed to be perfect florets. The following table shows that the results with current assumptions compared well with an earlier floret count with another type II head.

assumed counts actual count of
second head
reduced ligulate, pistillate 2216
eligulate, pistillate 3840
central perfect 1312
total: 7368

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