En EspaŅol

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
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
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


Daisy fleabane
Erigeron annuus

Prairie fleabane
Erigeron strigosus

More Plant Identification Questions

Unknown blue flower growing in New Boston, TX
May 18, 2013 - A light blue wildflower, similar to a cosmos, appeared in one of my beds this spring. I've never grown this flower and would like to identify it. The flower also has similarities to a passion flower...
view the full question and answer

Plant identification
April 20, 2010 - I am trying to identify a flowering plant (usually potted) that is commonly seen around homes in Phoenix, AZ. It has a long (1 to 1.5 ft) bare woody stem topped by an umbel of perhaps 15-20 small red...
view the full question and answer

Identity of mystery plant in non-native commercial forage mix
December 17, 2013 - Dear Smart One, I use a commercially prepared, fortified, chopped forage based on a mix of orchard and Timothy grasses. The bags are shipped in from out of State. However, I have been finding short s...
view the full question and answer

Identification of 3 small flowers in Hays County, Texas
June 25, 2012 - Trying to identify three (3) wildflowers growing on my property in the northwest corner of Hays Co, all very, very small blooms of about 1 cm. (roughly 1/4 inch): (1) small white blooms with five peta...
view the full question and answer

Identity of plant that resembles rosemary in Georgia
August 13, 2012 - Hi, I am an herbalist, but have been unable to identify this plant and it's driving me nuts since I cannot find any information on it. I live in NE Ga and have a plant that grows here that looks li...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP | STAFF
© 2016 Lady Bird Johnson Wildflower Center