Host an Event Volunteer Join Tickets

Your gift keeps resources like this database thriving!

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?

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 Seeds and Seeding Questions

Storing Rudbeckia Hirta Seed
October 10, 2014 - I just bought and planted your Rudbeckia hirta seed. I have a lot leftover. Can I store it until spring or better yet, next fall? If so, how?
view the full question and answer

Revegetating a hillside in western Washington state
October 10, 2012 - Removing several downed trees across my dock demolished the native plants growing on the hillside and the contractor pulled out their remains. The area faces east on an open freshwater bay. Close to...
view the full question and answer

Creating a bluebonnet patch between Brenham and Houston.
April 12, 2009 - I am creating a Bluebonnet patch in a well-drained section of my flowerbed. I just planted the plants (it is now early April and I'm between Houston and Brenham, TX). I plan to let them go to seed ...
view the full question and answer

Blackfoot Daisy care in Marble Falls TX
February 21, 2016 - I've planted and killed a number of blackfoot daisy plants. I know it's a hardy plant that, once established needs little or no care. But what about getting them started? What care do they need f...
view the full question and answer

Native grass mix for Bastrop County, TX
February 25, 2014 - I plan to put in a small lawn on a tract of land near Rosanky, TX in Bastrop County. There are scattered oaks but the yard space will be mostly open. Soil is basically sandy. Is there a good native...
view the full question and answer

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