Sunday, October 30, 2022

Calico aster - Symphyotrichum laterifolium

Calico aster (Symphyotrichum laterifolium) is a common aster native to much of north Florida and the Panhandle in partly sunny locations within deciduous woodlands and roadsides.  It also has been vouchered in every state east of the Mississippi River as well as a line from east Texas to the Dakotas and all of the Canadian provinces from the Atlantic to Manitoba.  Throughout this extensive range, it occurs in sandy to moist habitats, often in partial sun.  

Like most true asters in this genus, calico aster is a perennial wildflower that dies back in the winter and reemerges in the spring.  It produces a basal cluster of ovate leaves with dentate margins.  Multiple stems emerge and reach a mature height of 3-4 feet in the early fall.  The stem leaves are elliptical and numerous. The mostly hairless leaves have a characteristic hairy midrib on their back faces, and branching is usually horizontal or in what can appear to be a zigzag pattern. 

Flowering occurs in late summer to mid-fall.  The flowers of calico aster are small compared to most Symphyotrichum species. They have an average of 7–15 short white ray florets which are rarely tinted pink or purple. The disc flower centers begin as cream to yellow and often become pink, purple, or brown as they mature. There are roughly 8–16 disk florets, each with five lobes that strongly reflex (bend backwards) when open. Like other members of this genus, these blooms attract a wide variety of pollinators.

Calico aster is one of the asters that forms extensive colonies over time which may be one reason why it is so rarely propagated by native plant nurseries in Florida. It makes an excellent ground cover for open areas of a landscape, but does not play well in a smaller pollinator garden where diversity is desired. It is one of the asters that I have added lately to what I am growing at Hawthorn Hill.


Simmonds' aster - Symphyotrichum simmondsii

Simmonds' aster (Symphyotrichum simmondsii) is widely distributed in Florida and has been vouchered in nearly every county from the far western Panhandle to Miami-Dade.  Throughout its range, it is most common in open habitats with moist to well-drained soils.  Although it occurs throughout Florida, it is reported only from North and South Carolina outside of our state.

Despite its wide range in Florida, it has been virtually ignored by all of the current wildflower books and other publications in print.  It is a perennial forb that dies to the ground each winter and reemerges in early spring.  It reaches a mature height of 3-4 feet by late summer and the stems are rigid and semi-woody in nature. This is one of the aster species that suckers extensively and forms colonies over time.  The linear slightly recurved leaves alternate on the stems.  They are glabrous and clasp the stem without a defined petiole (sessile).  Each plant produces multiple stems.

Flowering occurs in the late fall to early winter.  The buds are produced at each of the leaf axils along the stem.  Each flower head is about 1 inch across. The petals are light lavender to purplish in color and may contain as many as 3 dozen narrow petals surrounding the yellow disc flowers in the center.  Like all members of this genus, they blooms are especially attractive to pollinators and it is likely that it serves as a host plant for the pearl crescent butterfly.

I am not aware of any native nursery offering Simmonds' aster for sale. It would make an excellent addition to an expansive planting area where it could sucker and form a large area of color and pollination services. It would not be appropriate for smaller areas of mixed wildflowers as it would overwhelm many of the other species over time. Although I have never grown it, it should be easy from ripe seed harvested in early winter.

The above photos were taken by Steve Coleman and are used with permission.

Barrens Silky Aster - Symphyotrichum pratense

Barrens silky aster (Symphyotrichum pratense) is not recorded as a native plant on the University of South Florida's ISB website, but it should be as it is recorded in Florida by a number of sources and occurs throughout the Southeast Coastal Plain from east Texas to Virginia and north from Arkansas to Tennessee and Kentucky.   The confusion may lie in the fact that it is often combined with western silver aster (Symphyotrichum sericeum) and considered to be a variety of it.  There are distinct differences, however.  Barrens silky aster is distinguished from S. sericeum by its much less densely hairy leaves and phyllaries, which are much larger and broadly ovate.  Their ranges overlap to a great extent.

Barrens silky aster occurs in a variety of sandy well-drained habitats from soils high in clay to loam and sand - including calcareous glades. The photos above were taken in such a habitat by my friend Lily Byrd and used by permission.  It is a perennial that dies back to the ground in winter and reemerges in early spring.  Barrens silky aster does not sucker aggressively as some in this genus. The singular stems reach a mature length of 2-3 feet by late summer.  They are sparsely hairy.  The ovoid leaves alternate on the stem and clasp it.  Like western silver aster, they appear silvery from a distance because of their short hairs - especially on the leaf margins.  

Like many asters, the rich lavender purple flowers appear in mid- to late-fall and occur at the ends of the stems. Each bloom is about 1 inch across.  They are visited by a wide variety of bees.

I am not aware of any native plant nursery in Florida or elsewhere within its range that currently offers barrens silky aster for sale.  Hopefully, this will change as awareness of the importance of asters to a pollinator garden increases.  If I can locate a source for seed, I would certainly add it to what I propagate at Hawthorn Hill.