Ampelaster carolinianus (Symphyotrichum carolinianum, Aster carolinianus)
Everyone who savors the native outdoors treasures personal fond experiences, often rooted in earlier memories. Something I’ve always loved in varied northern locales is wild Asters as the days grow cold and as the tree become stark branch silhouettes against the gray sky. Asters take me back to hikes on November days in Michigan where the Asters as the last wildflowers standing, say “hey, it’s not all that bleak.” A parallel experience applies more subtly on refreshingly cool November days around here. That took place last week on a class outing to the Grassy Waters Preserve with one of my all-time favorite species, Climbing Aster. Today, November 26, it is blooming with gusto in the Palm Beach State College Medicinal Plant Garden.
[Now a disclaimer, the name “Aster” used informally here embraces multiple genera in the Aster Family. Asters, including today’s species, tend to have complex nomenclatural histories.]
Capable of blooming some all year, in late autumn this species self-asserts with hundreds of fragrant flower heads near-white to pale violet, the younger heads with a yellow eye, and the older one dark-purple at the center. (The topic of changing eye color came up about a year ago in our article on Allapattah Flats and White Pine Barren Aster.)
Botany 101: what a flowering head in the Aster Family is all about. What looks like a single flower at first glance is a “composite” of many tiny flowers collectively disguised as a single bloom. But why? Here is one answer: A single pollinator visiting a “blossom” actually pollinates a hundred little flowers all at once. The tiny flowers come in two basic types: those “petals” around the periphery of the head are ray flowers. The eye is made up of numerous itsy bitsy “disc” (or disk) flowers. If you bust apart a flower head, and if your eyes are sharp, you can discern those individual flowers, complete with petals making a tube, stamens joined edge-to-edge into a tube, two stigmas, and an (inferior) ovary. The sepals are modified as the “pappus,” usually bristles or scales. The bristles become the parachutes familiar on the dispersing “seeds’ of many members of this family, such as Dandelions and Thistles.
The heads generally start out functionally male (pollen producing) before entering their female (pollen-receptive) phase. Glance at the diagram. The anthers form a tube, and they release pollen to the inside of the tube. The stigmas rise through the anther tube, plunging the pollen upward until it spills forth. Thus the pollen emerges from the tube before the stigmas pop out; they spread apart after emergence to begin the female phase.
To return to the species of the day, Climbing Aster is limited to the Southeastern U.S. in moist habitats from Florida to South Carolina and sort of North Carolina, where it may now be extirpated. (And yet is available commercially, so it may be secondarily un-extirpated as a domesticated native species yielding to the call of the wild.)
Climbing Aster is the only species of the genus Ampelaster, the genus name coming from Greek for vine-Aster. And this brings us to perhaps the most remarkable aspect of this species. Early in life it scrambles over other vegetation, making a mound of Climbing Aster on top of host plant(s). The Aster is not twining, and it has no tendrils. Instead, it rambles and sprawls. Aiding the climb, the vine makes lateral branches that tie the vine to the host and weave the mound together.
Oh yes, I promised something remarkable. Once the mound is formed, the Aster becomes woody. The wood and the intertwined branches become a self-supporting scaffolding, making the underlying host no longer necessary. We could re-name it “Strangler Aster.” To be redundant, this Aster makes its own trellis, hard, woody, reinforced by interlacing branches, and indestructible, perfect for its flood-prone riparian natural habitat.