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

Friday - April 26, 2013

From: Decatur, GA
Region: Southeast
Topic: Invasive Plants, Non-Natives, Herbs/Forbs
Title: Invasiveness of Cosmos from Decatur GA
Answered by: Barbara Medford

QUESTION:

I have been searching for an answer concerning the invasive plant Cosmos. I know that Florida declares this but I have not been able to find out does Georgia? And specifically,is it only the yellow Cosmos or all Cosmos found in nurseries?

ANSWER:

The only member of the Cosmos genus, member of the Asteraceae family, in our Native Plant Database is Cosmos parviflorus (Southwest cosmos). Since the Lady Bird Johnson Wildflower Center is committed to the growth, propagation and protection of plants native not only to North America (excluding Mexico) but to the area in which it is being grown, in your case, DeKalb County, GA, this would not ordinarily be in our realm of expertise. However, we are interested in invasive plants and their control, native or not. By the way, according to this USDA Plant Profile Map on Southwest cosmos, it grows in neither Georgia nor Florida, so it seems unlikely that is the plant in question.

So, we went searching on the Internet for a cosmos that had the potential to be invasive and found Cosmos sulphureus, Yellow Cosmos, which is native to Central America. Since you noted it was considered invasive in Florida, we found this article on Cosmos sulphureus in Floridata. This warning is at the bottom of that page:

"WARNING
Before planting orange cosmos check locally to make sure that it is not invasive in your area. In places like Tennessee orange cosmos is naturalizing in "disturbed" areas but so far is not disrupting native plant communities."

Floridata has the same warning on Cosmos bipinnatus, native to Mexico. In point of fact, Cosmos has been so intensively hybridized that understanding what invasive tendencies you observe in any one cultivar or selection is difficult. Hybrids do not breed true from seed, so the seeds you purchase or the plants you buy may have none of the characteristics you may expect, including invasiveness.  

For one last check, we went to the website of the Southeast Exotic Pest Plant Control article Invasive Plants of the Southeast. Cosmos was not on that list, native or non-.

 

From the Image Gallery




Southwestern cosmos
Cosmos parviflorus

Southwestern cosmos
Cosmos parviflorus

More Herbs/Forbs Questions

Container plants for cool weather in Cypress TX
October 02, 2011 - I am a novice gardener and I am looking for some ideas on potted plants for the fall/winter. They would be covered by a roof, but still susceptible to the elements. What can be planted now that will...
view the full question and answer

Plants for a lakeside bank in NC
November 07, 2011 - Our association is looking to plant a huge sloped area that runs down to Lake Wylie. We want to plant something that is good for erosion and that does not grow too tall so that we keep our view of th...
view the full question and answer

Companion planting with heartleaf skullcap from Arlington TX
April 24, 2011 - What can I plant with heart-leaf skullcap when it goes dormant in the summer?
view the full question and answer

Native Plants for Shaded North Slope in Ohio
January 03, 2013 - I have a shaded north hillside which needs erosion control plants. Mostly moss and very thin grass grows there now. Please help!
view the full question and answer

Wildflower Meadow for Poth, TX
January 22, 2014 - I recently cleared some underbrush from a virgin pasture, with large oaks and mesquites scattered through it, and was wondering if it was too late to plant wildflowers? If not, what varieties of wildf...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center