Bidens sp. in New Jersey

I am not an expert. This is what I've learned so far:

Bidens are fall wildflowers, some are restricted to wet areas, some are not.

There are two species that are simple to separate from the others:

-Spanish Needles (B. bipartita) has leaves twice compound.
-Beck's Water Marigold (B. beckii) is very rare, grows actually in water, and has underwater leaves that are hairlike and whorled.

That leaves four groups of species, separated by have rays / lack rays and simple leaves / once divide leaves.

Ray flowers present, and once divided leaves: Tickseed-Sunflowers:

-Tickseed-Sunflower (B. aristosa) 8-12 somewhat curled large green bracts below flower
-Marsh Tickseed-sunflower (B. trichosperma) 8-12 flat, broad green bracts below flower; long, skinny fruit
-Long-Bracted Tickseed Sunflower (B. polylepsis) 12-20 curled, long green bracts below flower
-White Beggarticks (B. alba): white rays (rare if present at all in NJ)

Ray flowers present, undivided leaves: Bur-Marigolds:

-Bur-Marigold (B. laevis): large rays, just like the tickseed sunflowers but note undivided leaves
-Nodding Bur-Marigold (B. cernua): short rays (1 in?) sometimes none, plant short (8 in?) on edge of water, always nodding. Sessile leaves.

No ray flowers, divided leaves: Beggarticks:

-Devil's beggarticks (B. frondosa): 5-10 large green bracts below flowerhead (extremely common)
-Tall Beggarticks (B. vulgata): 3-5 large green bracts below flowerhead
-Swamp Beggarticks (B. dicoidea): 10-20 large green bracts below flowerhead

No ray flowers, undivided leaves: Beggarticks (and Bur-Marigold)

-Beggarticks (B. connata): long, unwinged stem on leaf.
-Three-Pronged Beggarticks (B. tripartita): short, winged stem on leaf
-Nodding Bur-Marigold (B. cernua) when it lacks rays looks like these. Leaves have no stem.

Posted on Νοέμβριος 22, 2020 0325 ΜΜ by srall