The Developmental Stages of the Smooth Coneflower – Echinacea laevigata

Echinacea laevigata – the Smooth Coneflower – is among the rarest plants in North America.  It is not mentioned in the B. W. Wells classic The Natural Gardens of North Carolina.  More significantly, the historic habitat of the Smooth Coneflower (Piedmont Prairie or Piedmont Savannah) is not among the eleven natural gardens listed in his book, undoubtedly because these historic habitats existed during his lifetime only in tiny pieces.  The Smooth Coneflower is now found almost entirely in small, disconnected patches in four states: North Carolina, South Carolina, Virginia and Georgia.  It is federally protected under the Endangered Species Act and is state protected by the North Carolina Plant Conservation Program.

Echinacea laevigata
Smooth Coneflower

Conservation of the Smooth Coneflower depends greatly on habitat management, which emphasizes restoring the sites where the coneflower exists by thinning  trees (especially loblolly pines), and  utilizing a program of prescribed burns.   Some sites have unsustainably small populations; less than ten plants.  Augmentation of these sites, by growing plants from achenes specific to the site, is a helpful management tool and affords the opportunity to observe the biology and development of the Smooth Coneflower throughout an entire life cycle.

Achenes are technically a fruit, and those of the Smooth Coneflower look like little dry, wooden spear tips.  They require stratification to break down the woody shell and release the embryo to germinate.

Echinacea laevigata
Smooth Coneflower
Achenes

Echinacea laevigata
Smooth Coneflower
Achenes

The achenes germinate by releasing small, rounded embryonic leaves (cotyledons) in late February through April, with most germinating in March.  In field conditions, the small cotyledons are very difficult to find.

Echinacea laevigata
Smooth Coneflower
Cotyledon

In several weeks, a single true leaf emerges.

Echinacea laevigata
Smooth Coneflower
First True Leaf

More leaves come forth as the small plants grow.

Echinacea laevigata
Smooth Coneflwer
Young Plants

By late August, most of the coneflowers are fully developed.  Typically, they do not bloom until the second year of growth.

Echinacea laevigata
Smooth Coneflower
Mature Plants

In the second year, early flower buds begin to form in late summer and early fall.

Echinacea laevigata
Smooth Coneflower
Early Bud Formation

 

Echinacea laevigata
Smooth Coneflowers
Young Bud Maturing

The late stages of bud development can be as interesting as the mature flowers.

Echinacea laevigata
Smooth Coneflower
Late Bud Development

Full bloom shows the characteristic narrow, drooping, light pink petals of the Smooth Coneflower.

Echinacea laevigata
Smooth Coneflower
Blooming Flowers

Seedheads (technically achene heads) form, and the achenes mature over a wide period of time during the fall.  The achenes can be easily seen within the seedhead in the photo below.  Within a population of Smooth Coneflowers, the entire process, from the germinating of achenes to the ripening of seedheads, averages about seven months, from March through September.  From the perspective of an individual plant, the cycle from germination to ripe seedhead takes a year and seven months since they don’t bloom in the first year.

Echinacea laevigata
Smooth Coneflowers
Seed Head

The  federal Endangered Species Act requires that the U. S. Fish and Wildlife Service review the status of each listed species once every five years.   The five year review for Echinacea laevigata was just announced.  The Fish and Wildlife Service basically wants any new information about the species that has been observed or collected since the last review five years ago.  The hope is that management and protective measures are helping to stabilize and even expand the studied populations.

Echinacea laevigata
Smooth Coneflower
Mature Flowers

The common name of the Smooth Coneflower is derived from the very tall blooming stem that tends to be smooth and leafless, although small leaves can occur on the stems of some plants.

Herb Amyx

For information about the detailed rationale that  management uses to decide on augmentation, and the permits required, see the link to a previous article:

https://bwwellsassociation.wordpress.com/2015/03/25/saving-the-narrow-leaved-smooth-aster-symphyotrichum-laeve-var-concinnum/

 

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