Helianthus angustifolius is a branched perennial plant that is native to North America. This Facultative Wet species can found in hydric flatwoods and marsh communities as well as along the sides of ditches and roads that have mesic to saturated soils. Its brilliantly colored disk flowers make it easily recognizable as a member of the Asteraceae’s sunflower group – the Genus Helianthus. The swamp sunflower’s tall domesticated cousin, ‘the’ sunflower Helianthus annuus, is cultivated the world over for its nutritious seeds, oils and aesthetic value.
The swamp sunflower lacks rhizomes, and loses its basal leaves during the flowering season. The leaves of the lower stem are lanceolate in shape and transition from an opposite arrangement on the lower stem to an alternate one towards the top. The flowers of Helianthus angustifolius are either yellow or purple in color.
The Helianthus genus as whole is widely used to study diploid and polyploid speciation dynamics in plants. Helianthus angustifolius itself is typically phylogenically grouped with the species H. simulans and H. floridanus. All three sunflowers share common morphological features and have overlapping ranges (southeastern United States); however, only H. angustifolius will successfully cross with both H. floridanus and H. simulans.
The above plant photos were taken a couple of weeks back in the Florida Panhandle. The close-up with the lynx spider was featured with several other swamp sunflower pics in the prior post The Tactics of an Egg Tending Lynx.
As an administrative note, in the event that you’re tracking the Wetland Plant series, I’ve recently discovered that there’s been a miscount – I published two different posts with plants designated as Wetland Plant of the Week #25. To correct for this error this post has been numbered 37, but falls in line after Wetland Plant # 35.
TIMME (2007). HIGH-RESOLUTION PHYLOGENY FOR HELIANTHUS American Journal of Botany, 94 (11), 1837-1852