Open–head type with eligulate floret style branches exerted.
[Click to enlarge.]
Closed–head type with eligulate style branches barely visible.

Chaptalia texana Eligulate Pistillate Florets
by Bob Harms  email-here

Eligulate pistillate florets have short two–lipped (3–) 3.5–5.5 (–6.5) mm tubular corollas (roughly less than half the length of the style), just wide enough to enclose the lower portion of the style which rises from the achene apex c. 1 cm. The style branches at the very top; style branches c. 1.5–1.9 mm.

Prior to dispersal the structure of these florets is generally well concealed within the pappus bristles. For this reason, most measurements were from post–dispersal florets. No attempt was made to adjust for shrinkage of the dry florets.

eligulate florets of a well-developed type II–III head

open–head (type I)

closed–head type II (pappus cut to show corolla)

closed–head type III

Eligulate pistillate florets represented 47–63% of the total florets in a head (17–62 florets), the differences for the two types reflecting the fact that the open–head flowers contained more florets.
  percentage totals
open–head type 57–63% 54–62
closed–head type 47–60% 17–50
Eligulate floret length of open heads was on average 1.3 mm shorter than for closed heads:
  average length range
open–head type 9.2 mm 8.8–9.5 mm
closed–head type 10.5 mm 9.9–11.2 mm
Perhaps the most striking difference among the three main head types was the difference in length of the corolla tube.
  average length range% of floret length*
open–head (type I) 3.6 mm 3.1–3.8 mm 38%
closed–head: type II 4.6 mm 3–6.2 mm 46.5%
closed–head: type III 5.2 mm 4.5–6.2 mm 52.5%
*based on average lengths

Two anomalous open–head longer corollas were noted (shown below). The tube was just over 4 mm, but most interesting were the two long lips of each floret, the longer lips, 1.7 & 1.8 mm; the shorter lips, 0.4 & 1.2 mm respectively; and each with a prominent tip similar to those occurring with the 5–lobed central florets.

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