Flaveria linearis (Flavus is Latin for yellow.)

Asteraceae

Must be October, the Yellowtops glow goldenrod autumn,  rich canary yellow in wet meadows and beyond.  They’re a friend to many pollinators.  Fact is, it is fun to get among the plants and see what visitors show up.

Photos by John Bradford

No need to linger on a boring point of physiology, but it is my duty to point out that this species is an intermediate in terms of C3-C4 photosynthesis.   The first, C3, is “normal” photosynthesis, typical of temperate plants.   The second, C-4 photosynthesis, is a biochemical and anatomical specialization typical of many tropical plants.   A plant has to be one way or the other, or does it?

Three native Flaveria species grace Florida:  Two are intermediate C3-C4. They are F. linearis and F. floridana which DNA shows to be a narrowly distributed Gulf Coast offshoot of the widespread F. linearis.  What’s interesting is that F. linearis ranges into cooler north Florida and into the hot tropics.  Is that the benefit of having mixed temperate-tropical photosynthesis?

Our third native species, F. trinervia, is not closely related to the other two.  It is C4 and evidently a South Florida visitor from a worldwide tropical distribution…with surprising (brief?) cool-climate extensions.

Members of the Aster Family often dish out pollen in more complex and intriguing ways than are conspicuous at first glance.  So it is for Narrowleaf Yellowtops. The flowers are reluctant to release pollen until an insect comes probing and stomping.  Bug-pokes cause the little blossom to push out pollen within seconds of contact.   Watch it happen in the brief video below where a fake insect provokes pollen expulsion.

Pollen-pushing video. Be patient, the action is episodic and subtle:  PUSH HERE