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 thorny tree with lemon-like fruit
October 14, 2010 - What would be a small lemon like fruit that grows on a bush with large thorns? The fruit is about the size of a golf ball, kind of fuzzy yellow skin like a lemon and smells like a cross between an or...
view the full question and answer

Recognizing poison ivy
June 20, 2007 - I am having a difficult time identifying poison ivy. It seems so many plants look like poison ivy can you help me I don't want to kill everything but on the same hand I don't want to itch. Thanks f...
view the full question and answer

Blue vervain native to Indiana
January 06, 2003 - I have a species I need to know if it is native to my area (southern Indiana) - Blue Vervain (Verbena hastata)
view the full question and answer

Yellow-blossomed Shrub that Occurs in Arizona and Texas
May 08, 2012 - What is the name of the large shrubs you will see in Arizona with the bright yellow blossoms. They grow wild everywhere, and I also see them in the town. Could you please tell me the name of them, s...
view the full question and answer

Identification of an Australian tree.
November 29, 2007 - i have a tree i cant seem to find any info on, the tree has large almost heart shaped leaves with pinkish veins running through them, its not shiney anywhere, sort of a mat finish,the edges of the lea...
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