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

Monday - October 06, 2014

From: charleston, WV
Region: Mid-Atlantic
Topic: Seeds and Seeding, Wildflowers
Title: Silphium Perfoliatum Seeds
Answered by: Anne Van Nest

QUESTION:

I am trying to identify which part of the seedhead is the actual seed of the cup plant, Silphium perfoliatum. It is hard to find images. Some show the outer, larger, flat part of the seedhead which I thought was the husk. I always thought the seeds were contained inside that, but still visible when looking at the top of the seed head. There are lots of very thin/skinny parts inside the flatter parts. I can send a photo if needed, but was hoping you might have a photo showing which of the two is the actual seed. Hope I've described this well enough!

ANSWER:

Silphium perfoliatum, the cup plant is a dramatic perennial that grows up to 9 feet tall with yellow aster flowers during July – September. Each flower has 20-30 yellow ray petals and a darker yellow disk. Coarse foliage clasps the stem without a petiole and the small cup that is formed actually holds water. This feature attracts birds to the plant.

The plant is native to an extensive region from Southern Ontario to North Carolina and west to the Great Plains.

The deep roots make it difficult to transplant the cup plant, but it is easily propagated by seed. Collect the seed in September and October. Sow the unstratified seed in spring or stratify the seed (3 months of cold and moist treatment in the refrigerator) and sow it in the fall. Apparently goldfinches descend up the plant and devour the seeds.

The Illinois Wildflowers website has some additional information about the seeds. Each sunflower-like composite flower is about 3-4" across, consisting of numerous yellow disk florets that are surrounded by 18-40 yellow or pale yellow ray florets. The infertile disk florets protrude somewhat from the center and are rather conspicuous, while the ray florets are fertile. The latter produce thin achenes, each with a well-developed marginal wing, which are dispersed to some extent by the wind.

According to www.hort.net The fruit is a brown obovate achene with an emarginate apex, appearing in autumn. Sometimes 2-toothed.

Prairie Moon Nursery has a picture on the seeds on their website which shows the 2-toothed heart-shaped nature of some of them.

The Go Botany website has images and info from the New England Wild Flower Society and has an excellent slide show that has exactly what you need to see how and where the seeds are formed.

And finally, the USDA has a great closeup image of the Silphium perfoliatum seeds on their Plants Database website.

 

From the Image Gallery


Cup plant
Silphium perfoliatum

Cup plant
Silphium perfoliatum

Cup plant
Silphium perfoliatum

Cup plant
Silphium perfoliatum

More Wildflowers Questions

How do I grow bluebonnets in East Texas?
April 03, 2009 - I live in the Piney Woods region in N.East Texas. I bought a flat of bluebonnets and want to know if they will grow back next year? If not, how do I get bluebonnets to grow back every year in my yard ...
view the full question and answer

Something eating Monarda didyma in Washington DC
June 30, 2011 - Please Help, I have a couple of Bee Balm, Jacob Cline, plants, whose leave are being eaten, by what I do not know. None of the nurseries around here seem to have ever heard of this happening to this p...
view the full question and answer

Planting fields with wildflowers
November 05, 2009 - I'm hoping to seed a few fields (large area, short grass) the easiest way possible. I'd love to do bluebonnets but I don't think I can get a large aerator to the locations. Basically I'm wonderi...
view the full question and answer

Survival of bluebonnets in extreme heat from Tioga TX
September 03, 2011 - Is there anything I can do for my bluebonnet patch in this extreme drought for the rest of the summer and fall? Should I have watered this summer? I had a good show and think seeding was fairly normal...
view the full question and answer

Winter wildflower blooming in East Texas in the winter
October 06, 2009 - Is there a wildflower that will grow/bloom in east texas during the winter that can be tilled into garden in springtime. We put rye and red clover but were interested in getting some color/variety to ...
view the full question and answer

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