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 identification of Texas bullnettle (Cnidoscolus texanus)
September 15, 2009 - I'm trying to identify a small thorny plant that I found growing on our (previously undeveloped) dry lot in Hutto, Central Texas. It has small white flowers and green thorny bulbs. The leaves and st...
view the full question and answer

Mystery small tree with many large thorns
May 09, 2011 - In a small spot on over 2 acres, we have this strange tree/shrub. It is a single, straight stem with no branches, and has profuse, large thorns from top to bottom. At the top of the stem, the leaves...
view the full question and answer

Indentification of yellow four-petaled plant in Sonoma County CA
March 09, 2015 - Yellow four-petaled plant - low to the ground. Along the coast of CA in Sonoma County (near Bodega Bay) Might be Frying Pan but I can't find a decent description or the botanical name to look it up...
view the full question and answer

Plant identification
June 01, 2009 - I'm trying to identify a bush/shrub that is approx. 6 ft. with leaves like an azalea but has orange hot air balloon shaped balls that turn to small orange flowers. Blooming now in May. Dies back ea...
view the full question and answer

Smarty Plants on Parkinsonia aculeata
June 11, 2005 - What is the name of the tall shrub I see growing wild around Austin that is delicate, with thin stems and branches, and lacy, with multiple leaves, and yellow flowers? It looks lovely growing in a ma...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP | STAFF
© 2016 Lady Bird Johnson Wildflower Center