Rent Shop Volunteer Join

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 - September 12, 2011

From: New Braunfels, TX
Region: Southwest
Topic: General Botany, Plant Identification, Shrubs
Title: How can I distinguish Hibiscus laevis from Pavonia braziliensis in New Braunfels, TX?
Answered by: Jimmy Mills

QUESTION:

How can I distinguish Hibiscus laevis (Halberdleaf Hibiscus) from Pavonia braziliensis (Brazillian Rock Rose)? Earlier this year I was given the former by a friend and former NPSOT chapter President. Then I bought a Salvia at Medina Garden Nursery, and it had a "volunteer" in the pot that they identified as "South American" Rock Rose. Now both are blooming, and they appear almost indistinguishable. Thanks,

ANSWER:

Both Hibiscus and Pavonia are genera in the plant family Malvaceae, so you would expect them to resemble one another; one source referred to them as cousins, but lets not go there. When Botanists describe plants and assign them to genera and species, a great deal of attention is paid to the structure of the flowers in addition to other morphological and chemical characteristics. There is one difference in the flowers of these genera that is easy to see, and will allow you to distinguish Hibiscus from Pavonia. Luckily, you have flowers of both plants.

Before we go into flower parts, look at this diagram to refresh your memory. We are interested in the pistil which is composed of the ovary, style(s) and stigma(s).

One character that separates the two genera is the number of stigmas at the tip of the pistil. Plants in the genus Hibiscus have the style divided into 5 stigmas, while plants in the genus Pavonia  have twice as many stigmas (10).

In the case at hand, the common name of Hibiscus laevis (Halberdleaf rosemallow), or Halberdleaf Hibiscus gives us another clue. The halberd was a type of pole axe used in the middles ages, whose shape somewhat resembles the base of the leaf of H. laevis (or vice versa).

The following links illustrate these features:

Alabamaplants.com  pictures of the stigmas and leaf shape in H. Laevis.

Greatstems.com  pictures of stigmas of Pavonia braziliensis

Greatstems.com  good illustration of stigmas in a Texas Pavonia, P. lasiopetala. Also note the leaf shape

 

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

Half-life of the insecticide imidacloprid
March 07, 2011 - How long do systemic insecticides such as imidacloprid (Merit) remain active in nursery grown plants? Asclepias curassavica (tropical milkweed)is frequently grown with imidacloprid to prevent...
view the full question and answer

Genetics reason for color variation in Indian paintbrush
April 03, 2005 - Are the color variations in Indian paintbrush (Castilleja indivisa) a matter of genetic mutation or minerals in the soil? I say it's genetic and the rest of the family says it's environmental.
view the full question and answer

Plant for science experiment from Kentfield CA
November 10, 2009 - What is a fast growing plant I should use for a science experiment?
view the full question and answer

Water Use Versus Soil Moisture
October 14, 2014 - In the Native Plant Database, under Growing Conditions what is the difference between water use and soil moisture? Sometimes they seem contradictory.
view the full question and answer

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