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

Wednesday - January 30, 2008

From: Carrollton, TX
Region: Southwest
Topic: Plant Identification
Title: Identification of plant, possibly giant ragweed (Ambrosia trifida)
Answered by: Nan Hampton and Joe Marcus

QUESTION:

I am trying to identify a weed that was prevalant where I grew up in North Central Texas. It grows in low spots and along creeks. It has woody stalks with short spines, grows 3'- 6' tall, the leaves are braod and spiny also, and when you break the stalk, it bleeds red sap. It grows in huge clumps and will take over a creek bank.

ANSWER:

The plant that best fits your description is Ambrosia trifida (great ragweed) or, more precisely, Ambrosia trifida var. texana (Texan great ragweed). It grows in waste places and, although native, it is considered invasive in some areas. One of its common names is blood ragweed and the description in Shinners & Mahler's Illustrated Flora of North Central Texas, p. 310, for Ambrosia trifida L. var. texana reads:

"...sap blood red.. . The sap stains the hands red if the tissues are damaged."

Here are additional photos of Ambrosia trifida (giant ragweed) from the University of Texas "Image Archive of Central Texas Plants" and still more photos from the Freckmann Herbarium, Universtiy of Wisconsin.


Ambrosia trifida var. texana

Ambrosia trifida var. texana

Ambrosia trifida var. texana

 

 

More Plant Identification Questions

Identification of vine in Pennsylvania
June 11, 2012 - I have several vine plants growing in my deck planters from last season. The leaves are 9 pointed, it looks more like 7, but there are 2 little points at the very bottom of the larger leaves. When t...
view the full question and answer

What is a Demaree Rose?
August 14, 2013 - Have been told the Apache Plume is the Wild Rose after which the Wild Rose Pass north of Ft. Davis was named. However, other research indicates it was the Demaree Rose. What is true and are there ...
view the full question and answer

Identification of a Globe Mallow
March 14, 2008 - Mr. SP, Two or three years ago I purchased a mallow at the Wildflower Center that (I was told) had not yet been identified. I have looked at your pictures of Sphaeralcea hastulata which has the same ...
view the full question and answer

Plant identification, Chinese Lantern
September 06, 2007 - I have a plant growing along my fenceline that I am unsure of what it is. Some ppl have said it is a rare Chinese Lantern plant. I looked that up and it doesn't match. The plant right now sits about ...
view the full question and answer

Smarty Plants on Hesperaloe parviflora
August 22, 2005 - On your home website there is an orange flower that is tall and has tall leaves. is it a cactus? Thanks.
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