En Español

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

Tuesday - November 15, 2011

From: Austin, TX
Region: Southwest
Topic: Propagation, Seeds and Seeding, Trees
Title: Mexican Sycamore trees grown from seed
Answered by: Jimmy Mills

QUESTION:

If someone is selling an alleged Mexican Sycamore grown from a seed harvested from a mature tree growing in Austin, is it likely to be a TRUE Mexican Sycamore -- or has it most likely been pollinated by an AMERICAN Sycamore, such that the resulting hybrid has an unpredictable mix of M. Sycamore and A. Sycamore traits? I have wondered because when almost every such tree I've seen for sale in Austin has leaf undersides which usually seem to lack the silvery sheen [or at least whitish cast] and/or the fuzzy underside that I've always assumed was the mark of a TRUE Mexican sycamore. How can I know if I'm getting "the real deal"? Are these trees simply hybrids at best -- and not true Mexican Sycamores?

ANSWER:

You seem a little skeptical which is a good thing.

Lets learn a little more about Sycamores. The American Sycamore is Platanus occidentalis (American sycamore), and the Mexican Sycamore is Platanus mexicana.
P. occidentalis is native to the U.S., but P.mexicana is native to Mexico and therefore is not found in our NPIN Database. The Mexican sycamore has become popular in the last ten years as an introduced ornamental.

Sycamore trees are monoecious, having both pistillate (female) and staminate (male ) flowers on the same plant. However, it is doubtful that they are self-fertile,  ie. pollen from staminate flowers can not pollinate pistillate flowers on the same tree.  The trees are also wind pollinated. Since P. occidentalis and P. mexicana are closely related, it is not out of the question that they are able to cross pollinate and produce viable hybrids. So there is no way of knowing if the seed from which the tree being sold grew was the result of pollination from P. mexicana  or  from P. occidentalis. The odds of the tree being a hybrid seems pretty high unless the seed parent was growing in a grove of P. mexicana.

How can you tell the difference? One character that is easy to see is the the shape of the leaves. The link to austintreeexperts.com  says that P. occidentalis leaves are broader at the base, and will generally have an extra lobe that is lacking in P.mexicana. There are two photos on the link that show this distinction.

These two links from the Texas Forest Service have illustrations that also demonstrate this feature:

    Platanus occidentalis

    Platanus mexicana    mentions the silver underside of the leaf

Your best source of a TRUE Mexican Sycamore is to find one that was vegetatively propagated.

 

More Propagation Questions

Propagation of Blackfoot daisy seed
July 21, 2015 - I have a three yr old Blackfoot daisy. How do you root Blackfoot daisy seeds? When is the best month to grow these seeds?
view the full question and answer

Transplanting birdwing passionflower in Canyon, TX
April 17, 2009 - First, thank you for all your help! Second, I have two bird-wing passionflowers that are growing next to the house. I'd like to move them because this is the area where I want to put in some raise...
view the full question and answer

Identifying gender of persimmon trees
October 23, 2006 - How can you tell the difference between a male persimmon tree and a female persimmon tree? Also do you need both to bear the fruit? I live in Louisiana and never heard of this before. Thanks.
view the full question and answer

Planting Candelilla from Austin
July 12, 2013 - Good Morning and thank you for answering my question!! I am interested in planting a Candelilla plant (it looks like small bamboo plants growing only a 2-3 feet tall. I heard it is supposed to be ver...
view the full question and answer

Smarty Plants on potted plants
May 23, 2005 - How do you know when it is time to transfer a potted plant to a bigger pot? Everytime I do this my plant dies.
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