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 blue wildflower on roadsides in Massachusetts
July 28, 2012 - What is the blue wildflower planted on roadsides and highways in Massachusetts?
view the full question and answer

Plant identification
July 18, 2010 - My daughter is working on a wildflower collection for her Biology class, we have found a flower, that, for appearances sake, is identified in books as Selfheal. This flower is taller than pictures we...
view the full question and answer

Identification of Beetleweed or Galax as
February 28, 2006 - My mother will soon celebrate her 100th birthday. For her 1st birthday her mother decorated her highchair with "smilox". I am trying to find out what plant this is. I have found "smilax" but it is...
view the full question and answer

Identifying plant
October 21, 2007 - What plant is usually found growing in low-lying freshwater marshy places with a single, straight-stemmed plant that grows to about one-to-two feet in height. The branches and leaves are sparse with ...
view the full question and answer

Plant identification
May 30, 2012 - I had a strange plant pop up in my yard this year, and I figured maybe you guys could help me out. This plant is spreading along the ground, and the stem is woody right where it is coming out of th...
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 | STAFF
© 2015 Lady Bird Johnson Wildflower Center