Host an Event Volunteer Join Tickets

Support the plant database you love!

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

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
1 rating

Monday - May 27, 2013

From: Austin, TX
Region: Southwest
Topic: General Botany, Plant Identification
Title: Differences in prostrate Mimosa species
Answered by: Nan Hampton

QUESTION:

There are apparently a lot of little pink puffy-flowered prostrate plants with thorny stems and sensitive leaves: Mimosa microphylla, Mimosa roemeriana, Mimosa strigillosa. How does one tell them apart?

ANSWER:

You can find a key that lists the differences between two of the three species that you mention— Mimosa strigillosa (Powderpuff) and Mimosa roemeriana (Roemer's mimosa) —plus several other species—in the online version of Shinners & Mahler's Illustrated Flora of North Central Texas on p. 677-682.   Mimosa microphylla (Catclaw sensitive briar) is not included in that volume.

From Shinners and Mahler's key, M. strigillosa is described as:

"Plants with numerous weak, hair-like or bristle-like structures not painful to the touch; recurved prickles absent; mature fruits 10-20 mm long, noticeably flattened, with numerous suppressed hairs on the surface."

M. roemeriana is described as:

"Plants conspicuously armed with numerous recurved prickles capable of causing pain."

This also applies to: 

Mimosa nuttallii (Nuttall's sensitive-briar), Mimosa latidens (Kairn's sensitive-briar) and Mimosa hystricina (Porcupine mimosa)

You can read how Shinners and Mahler's separates these four species.

These four species, plus Mimosa microphylla, were once classified in the genus Schrankia.  A part of the general description (according to Correll and Johnston's Manual of the Vascular Plants of Texas, pp. 775-6) of the genus Schrankia is:

"...armed with numerous recurved prickles (or very rarely the prickles absent)..."

Their synonyms under that genus are:

Synonym for M. roemeriana is:  Schrankia roemeriana.

Synonym for M. nuttallii is:  Schrankia nuttallii.

Synonym for M. latidens is:  Schrankia latidens

Synonyms for M. hystricina are:  Schrankia hystricina and Schrankia nuttalli var. hystricina.

Synonyms for M. microphylla are:  Schrankia angustata, Schrankia microphylla and Schrankia uncinata.

The five species are then separated by:

  • "Leaflets with raised reticulate veins beneath" and "Legume 1-4 cm. long, rounded at apex; peduncles 4-12 cm. long; flower heads in early bud with protruding bracts." S. hystricina = M. hystricina.
  • "Leaflets with raised reticulate veins beneath" and "Legume 4-12 cm. long, acute or beaked at apex; peduncles 2-7 (-10) cm. long; flower heads in early bud with bracts completely hidden."  S. uncinata = M. microphylla.
  • "Leaflets smooth or the midvein prominent only" and "Lower portion of stem distinctly 4- or 5-sided, glabrous; stipules small, 1-3 (-4) mm. long; pod 4-sided, scarcely flattened at maturity; plants of southern Texas."  S. latidens = M. latidens.
  • "Leaflets smooth or the midvein prominent only" and "Lower portion of stem rounded, not distinctly 4- or 5-sided; stipules 3-6 mm. long; pod various" and "Mature legume 4-7 (-8) cm. long, flattened, the valves 3 to 6 times as wide as the thickened margin; pinnae 2 to 5 (or 6) pairs; leaflets mostely obtuse at apex; plants of central and north-central Texas."  S. roemeriana = M. roemeriana.
  • "Leaflets smooth or the midvein prominent only" and "Lower portion of stem rounded, not distinctly 4- or 5-sided; stipules 3-6 mm. long; pod various" and "Mature legume 6-12 cm. long, tetragonal, not conspicuously flattened or if so the valves less than twice as wide as the margin: pinnae (3 or) 4 to 8 pairs; leaflets mostly acute at apex (rarely obtuse throughout); plants of eaternmost or westernmost Texas" and "Stems, ovary and pod completely glabrous; plants of east Texas."  S. microphylla = M. microphylla.

This is probably a lot more information than you wanted, but you can see that it can be complicated to distinguish between the species.   To complicate things a bit more, the synonyms for M. microphylla have two different descriptions and I wasn't able find the current description for M. microphylla.

Since you live in Travis County I can tell you that M. roemeriana is the species you are most likely to encounter in the county.  Local botanist, Bill Carr, has also reported M. strigillosa and M. nuttallii as occurring here

In case you could use some help with the botanical terminology, we have a Glossary of Botanical Terms you can consult online.

 

From the Image Gallery


Roemer's mimosa
Mimosa roemeriana

Powderpuff
Mimosa strigillosa

Littleleaf sensitive briar
Mimosa microphylla

Nuttall's sensitive briar
Mimosa nuttallii

Kairn's sensitive briar
Mimosa latidens

More General Botany Questions

Trillium phototropism
May 16, 2010 - I'm SURE you haven't had this question before. I live in northern Michigan in a wooded subdivision where we have clouds of wild grandiflorum trilliums growing in the woods on either side of the roa...
view the full question and answer

Manzanita struggling in CA
March 01, 2012 - I live in Monterey, CA and I have had a manzanita (either Dr. Hurd or Mt. Hood) growing successfully in my yard for about 4 years. This fall all the leaves turned brown and brittle. I am not sure if d...
view the full question and answer

Which plants grow well together
April 17, 2009 - Please tell me what plants grow best together and which plants do not grow very good together
view the full question and answer

Flower color in shooting stars (Dodecatheon meadia)
February 25, 2010 - Shooting Stars (Dodecatheon meadia) come in the colors white, lavender and purple in the eastern U.S. Is this just genetic variability or does soil chemistry affect the flower color?
view the full question and answer

Percentage of flowers that close up at night
July 19, 2007 - Percentage-wise, approximately how many species of flowers close up at night? Is there a list anywhere?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.

Bibliography

Manual of the Vascular Plants of Texas (1979) Correll, D. S. & M. C. Johnston

Shinners & Mahler's Illustrated Flora of North Central Texas (1999) Diggs, G. M.; B. L. Lipscomb; B. O'Kennon; W. F. Mahler; L. H. Shinners

Search More Titles in Bibliography