Contact Us Host an Event 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
Not Yet Rated

Friday - February 15, 2008

From: Vienna, Austria
Region: Other
Topic: Trees
Title: Is western soapberry (Sapindus saponaria var. drummondii) dioecious?
Answered by: Nan Hampton

QUESTION:

Hi! I found different information on the flowering habits of the western soapberry, Sapindus saponaria var. drummondii. Is it dioecious or polygamo-dioecious or none of them? I have some little seedlings growing, planning to use the fruits for soap in the future. so the flowering habits are important to know for me. How old must the western soapberry be to start flowering? Thanks!

ANSWER:

The mating system of Sapindus saponaria var. drummondii (western soapberry) is, indeed, confusing. Here are what the following sources say about it:

1. In "Manual of the Vascular Plants of Texas" Correll and Johnston say about the Family Sapindaceae: "...staminate and pistillate flowers on separate plants or often some flowers appearing perfect;..." They give no specific description for Sapindus saponaria var. drummondii.

2. In "Trees and Shrubs of the Trans-Pecos and Adjacent Areas" Powell says about the Family Sapindaceae: "Flowers small, unisexual, male and female on separate plants, or flowers perfect, borne in clusters,..."  Again, there is no specific description for Sapindus saponaria var. drummondii.

3. In "Field Guide to Texas Trees" Benny Simpson says about S. saponaria var. drummondii: "Male and female flowers occur on separate trees, and in the deep sands of the Rolling Plains, groves of one to ten acres can be found that are apparently of only one sex. One or several trees spread vegetatively by rhizomes, creating these large groves. The clusters of white flowers produced in May or June must be inspected closely to tell whether the tree is male or female."

4. Information from the U.S. Forest Service says that S. saponaria var. drummondii is dioecious.

5. Finally, in "Forest Trees of Oklahoma: How to Know Them" Little says about Sapindus drummondii (syn.= S. saponaria var. drummondii): "Flowers many, almost stalkless, mostly male and female...."

So, I think you can probably expect your trees to be dioecious with either staminate (male) or pistillate (female) flowers, but don't be surprised if there are a few perfect (with both male and female parts) flowers scattered about on some of the trees.

Now, how long it will be until they bloom? This is another question we can't answer precisely. The U.S. Forest Service describes S. saponaria var. drummondii as being moderately slow growing and the Texas Forest Service Texas Tree Planting Guide describes its growth rate as moderate.

Here are a couple of quotes from the "Manual of Woody Landscape Plants" by Michael Dirr describing growth rate of trees:

"Rate of growth refers to the vertical increase in growth unless specified differently. Rate, as is true for size, is influenced by numerous variables such as soil, drainage, water, fertility, light, exposure, ad infinitum."

"The designation slow means the plant grows 12" or less per year; medium refers to 13 to 24" of growth; and fast to 25" or greater."

This, of course, doesn't answer when they might bloom. That, too, will depend on a number factors similar to those associated with growth. I would think, however, that it would be 4 to 5 years before they are as tall as 5 or 6 feet. They might possibly bloom by then. This is a lot of arm-waving, I know, but I'm afraid that's about the best I can do for you.


Sapindus saponaria var. drummondii

Sapindus saponaria var. drummondii

Sapindus saponaria var. drummondii

Sapindus saponaria var. drummondii

 

 

More Trees Questions

Replacing mature Arizona Ash trees in Austin
August 26, 2011 - Mr. Smarty Plants, I have 2 very large, very old Arizona Ash trees in my yard. I want to remove them and replace them with something like Cedar Elm or Chinquapin Oak. The problem is that they are t...
view the full question and answer

Stopping erosion on bank of a Florida retention pond
July 21, 2015 - I live on a retention pond, which has had all vegetation killed by the lake doctor. As a result the bank has eroded so there is a drop off directly to the water rather than a sloping bank. What plan...
view the full question and answer

When does Ziziphus obtusifolia leaf and flower in Austin?
March 22, 2010 - Hello Mr. S.P., Do you know when the Texas buckthorn, Ziziphus obtusifolia (I believe), flowers (and leafs out) in Austin? Is there one at the Wildflower Center?
view the full question and answer

Disease or insect damage on a Mexican plum
September 08, 2013 - Help, Our Mexican plum tree is about 13-14 years old. Earlier this year we noticed the trunk is oozing black stuff and whole branches are dying off. We have watched as our beloved tree has lost most ...
view the full question and answer

Ecosysystem with pecan at center from Austin
February 21, 2014 - Dear Mr. Smarty Plants, I would like to create a native tree guild around a mature pecan. It shares its space with native shrubs and ephemerals but I would like to add a nitrogen fixing plant. I am...
view the full question and answer

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