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

Plant ID in Crossville TN
July 12, 2009 - I live in Crossville TN and have found a common plant on hikes in the state park. It has long (1-1.5)narrow leaves that are green and deep red? What is it please?
view the full question and answer

Identification of vine from Las Vegas NV
July 11, 2012 - I'm interested in identifying the vine shown by the leaf in this photo: https://picasaweb.google.com/lh/photo/zR3R4JSPYcCI4ESczNXWM4h8z33Cq5cyZNqSSYf9hx0?feat=directlink My mother-in-law got one o...
view the full question and answer

Books on Lilies
August 27, 2006 - Dear Sir, I am looking for a book covering the Lily Family as a whole, i.e., it should preferably also discuss other Genera than Lilium only. I am especially interested in Lily members occurring in t...
view the full question and answer

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

Weed identification
February 27, 2012 - Weeds / Wildflower. I dream of a photo identification for weeds / wildflowers that pop up in my garden here in Austin, Texas. Maybe I don't want to pull them up. How do I know? Do you know of a b...
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