Contact Us Host an Event Volunteer Join

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
Not Yet Rated

Thursday - July 07, 2011

From: Grinnell, IA
Region: Midwest
Topic: General Botany, Plant Identification
Title: Difference between Erigeron strigosus and E. annuus
Answered by: Nan Hampton

QUESTION:

How can you tell the difference between Erigeron strigosus or Erigeron annuus. Does one have more flowers on it than the other? Thanks.

ANSWER:

As you have already discovered, I'm sure, the differences are not obvious.  In fact, they are VERY subtle.  Erigeron strigosus (Prairie fleabane) was once considered a subspecies of Erigeron annuus (Daisy fleabane).  (Erigeron annuus ssp. strigosus is the synonym for the accepted name Erigeron strigosus var. strigosus.  See the entry from ITIS–Integrated Taxonomic Information System.)

You can read a description of E. strigosus and a description of E. annuus from eFlora.org, the online version of Flora of North America.  There are many technical botanical terms used in the description.  If you have James Harris' excellent book, Plant Identification Terminology, you shouldn't have any problem working your way through the terms.  If you don't have Harris' book, here are a few sites that should help you.  For leaf shape, try the Berkeley Echo Lake Camp Leaf Shape Terms and Leaf Shapes and Arrangements from The Seed Site.  You can find a very good list of Botanical Terms on the Calflora.net site.  Reading through and comparing the descriptions, you can see there are small differences in the types of hairs on the stems and leaves, the leaf shapes and whether the leaves persist during flowering.  You will also note there is considerable overlap in sizes and numbers of structures.  E. annuus is listed as having 5–50+ flower heads and E. strigosus is shown as having 10–200+, but still there is some overlap.  Just to complicate things more, please note the statement at the end of the description of E. annuus:

"Apparent intermediates between E. annuus and E. strigosus are encountered."

If you go to the 'parent' page for Genus Erigeron on eFloras, you will see that the the genus is divided into 23 Groups.  E. annuus and E. strigosus are part of Group 4.   The key to Group 4 of Erigeron spp. summarizes the differences in the two species and is a bit easier to get through; but, as you will see, there is still overlap in the descriptions and you are going to need a magnifying glass to see some of the differences.

Good luck in distinguishing between the two!

 

From the Image Gallery


Eastern daisy fleabane
Erigeron annuus

Prairie fleabane
Erigeron strigosus

More Plant Identification Questions

Plant identification from Alpharetta GA
September 28, 2009 - I found a thorny bush in a yard. It had either immature fruit or a seed pod that I would like identified. The pod was a little larger than a golf ball, yellow, and a little fuzzy. When cut open it ...
view the full question and answer

What are the cone shaped evergreens around Pilot Point, TX?
January 26, 2016 - What are the cone shaped evergreens around Pilot Point, Texas called? They are dark green with spiky leaves and rough bark. I have a row planted as a windscreen and want to transplant a couple from a ...
view the full question and answer

Mystery Iris-like plant in Tennessee
September 02, 2008 - What is this flower? It came up and bloomed for about five days then died. It was a beautiful white trumpet shaped flower. It had one stem with four flowers. It came up like an Iris but we nver plante...
view the full question and answer

Identification of Tacoma stans or Yellow Bells
September 05, 2006 - We have seen a plant along the freeway here in Round Rock...beautiful greens leaves and the most amazing yellow flowers. Someone told us it was an esperanza plant and drought tolerate; however, I can...
view the full question and answer

Help identify a plant.
February 21, 2008 - Could you help me to identify this plant?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.