Artificial key for Chaptalia in Texas

by Bob Harms 

1. Ligules of peripheral florets with a purple midstripe beneath at anthesis; disk florets (functionally staminate) more numerous than internal pistillate florets; SE Texas coastal plain.

C. tomentosa (Florida) [From photos by Scott Namestnik.]

1. Ligules of peripheral florets when present uniformly cream colored on both sides at anthesis; internal pistillate florets much more numerous than disk (perfect) florets; central, south and west Texas. (For floret counts)

C. texana

2.

• Phyllaries rigid, subulate and subulate-linear, imbricate, typically greater than 1.5 mm wide in the middle;
• pappus 10.5—13.6 mm long;
• leaves typically epetiolate or with short petioles;
• ligules of spring florets, when visible, barely extending beyond the phyllaries and blocked from spreading outward by stiff phyllary tips;
• heads not heliotropic.

Ligulate florets & phyllaries (C. carduacea (left) & C. texana)

2.

• Phyllaries flexible, linear-lanceolate, subimbricate, ±1 mm wide in the middle;
• pappus 8.5—10.5 mm long;
• leaves typically petiolate;
• ligules of spring florets extending beyond the phyllaries, spreading outward from the involucre at midday and closing in the evening;
• heads heliotropic.