In spring 2006 we conducted two big seedling growth experiments at the Chicago Botanic Garden. This page describes some of the major activities.

Background
Flowering Phenology Experiment
Inbreeding/Outbreeding Experiment
Weighing Achenes
Germinating Seeds
Planting Sprouts
Photographing Cotyledons
Measuring Seedlings
Sampling Tissue
Driving to Minnesota
Preparing the Site
Planting Seedlings
Watering Seedlings
Entering Data
Future Activities
Thanks to all the Volunteers
Acknowledgements


Background

Human activities have fragmented the once vast, continuous tallgrass prairie and great plains into small, isolated patches of habitat. We use Echinacea angustifolia as a model prairie species, we hope to understand their biology better to help conserve these remnant populations.

Flowering Phenology Experiment
Lead investigator Jennifer Ison, UIC

Jennifer's research focuses on how the flowering phenology of individual plants shapes within population gene flow. We monitored flowering time of all common garden plants in 2005 and she will determine the paternity of the seeds to get a direct measure of gene flow. This has implications for conservation--specifically seed harvesting. Seed collectors often visit a site only once, at the height of seed maturity; thus seeds set early or late the season are not represented. She is interested in how this non-random seed harvesting affects the genetic diversity in the seed collections.

Echinacea angustifolia
The study species. top

Inbreeding/Outbreeding Experiment
Lead investigator: Andrea Southgate, NU

Andrea is investigating the effects of inbreeding and outbreeding as it relates to population size. She has germinated Echinacea seeds derived from three hand pollinated crossing types: (1) within family, (2) within population, and (3) between population.

Helen and Steph hand pollinating in the CG in 2004
Hand pollinating in 2004. top

Weighing Achenes

In order to determine whether the harvested achenes for each experiment contained viable embryos, each individual achene had to be weighed. Many people helped to weigh a lot of achenes. For example Art weighed 11633 achenes, Char: 4399, Amy: 1723, Erin: 58, Elaine: 552, Josh: 205, Marita: 311, and Mary: 710.

Art weighing achenes Char weighing achenes
Art & Char weighing achenes. top

Germinating Seeds

The seeds with viable embryos were placed into 375 Petri dishes lined with blotter paper with the help of Josh, John, and Erin. Each dish was watered initially and then as needed with a solution of water and ethylene, a growth hormone. The dishes of achenes spent two weeks in a cold treatment (4° C) under low light, then put into 25° C incubators set with a 16 hour on/ 8 hour off bright light cycle. After one week in the incubator, achenes were checked daily for sprouts.

Placing achenes
Placing achenes. top

Planting Sprouts

Over 5400 sprouts were planted into the plugs of 30 trays (220 plugs per tray). In order to ensure the sprouts were planted randomly, the plug planting for each tray was randomly ordered. 21 people and 230 datasheets later, the sprouts were planted and the trays were placed in the mist room of the greenhouse. Five days later the plug trays were moved into the greenhouse.

Planting sprouts 1 Planting sprouts 2 Planting sprouts 3
Planting and planting and planting sprouts. top

Photographing Cotyledons

Seven days after they sprouted, the seedlings in the inbreeding study were photographed. Jim, Jenny, and Sue created 1980 labels, cleaned 1600 seedlings, and focused and photographed 1700 7-day old plants.

A 7-day old seedling
One of 1700 photos. top

Measuring Seedlings

We measured the height of all 5400 seedlings when they were 14 days old to determine their vigor and growth rates. Additionally, we measured Andrea's 1500 seedlings when they were 21, 28, and 35 days old. These volunteers braved the visual jungle of the plug trays to measure heights of all Echinacea leaves to the nearest millimeter: Theresa: 268, Amy: 555, Elaine: 97, and Debra: 660. These volunteers recorded the measurements with unprecedented precision: Jim: 3960, Art: 880, Emily: 220, Char: 880, Theresa: 2200, Elaine: 1100, and Debra: 440. Here are the average heights of the longest leaf per plants: 17.2 mm (day 14), 35.6 mm (day 21), and 43.2 mm (day 28).

Measuring plants. Many plants in greenhouse.
Measuring plants--lots and lots of plants. top

Sampling Tissue

In Jennifer's experiment, it is important to know the parents of her seedlings, so she can relate the flowering time of the parents to that of the offspring. The mothers are known because they are the plants from which the seeds were collected. Jennifer will use Microsatellite loci (DNA fingerprinting) to determine the fathers. Volunteers Jim, Theresa, Art, Debra, and Elaine cut labels and stuffed 4620 small plastic bags with 4000 tissue samples.

Who's your daddy?
Maggie & Char at work. top

Driving to Minnesota

Stuart custom built shelves for the Garden's Chevy Blazers to transport 30 plug trays of Echinacea. The 5400 plants comfortably traveled the 9+ hour drive from the Chicago Botanic Garden's Greenhouse to return to the prairie of their parents near Kensington, Minnesota.

Plants packed up and belted
Are there enough seatbelts for every plant? top

Preparing the Site

Two sites were planted in 2006: a Minnesota DNR Wildlife Management Area, and the common garden. To prepare the WMA site, John tackled gopher mounds to mow the 100 m x 70 m site. Gretel, Jennifer, and Andrea embraced geometry and huge measuring tapes in order to create a 80 m x 50 m plot with square edges and straight lines, flagged at every meter. To prepare the common garden, Stuart and Gretel geared up with water packs and a drip torch to conduct a controlled burn of the area

Set up.
Preparing the site for planting. top

Planting Seedlings

It took two days and over 200 person-hours to put the Echinacea seedlings into the ground. Here's the procedure: (1) Two people laid out 50 m tapes in perfectly straight lines on which to plant the seedlings. Such precision is necessary for finding small plants in tall grass later and for maintaining the identity of the plants via their position. (2) A dibbler (a person using a dibble) followed this measuring tape and created a ~8 cm hole, or dibble hole, every meter for Jennifer's experiment or every half meter for Andrea's. (3) The next person generously watered each individual hole. (4) On hands and knees, a planter securely placed a designated Echinacea seedling in each hole and tucked it in. (5) Steps 1-4 were repeated until, after much effort, all seedlings were in the ground.

Planting seedlings Watering seedlings
Dibblers dibbling & planters planting. top

Watering Seedlings

In addition to watering dibble holes just before planting, the sprouts required watering after they had entered the ground to ensure success. Stuart and Sonja worked with the Minnesota Department of Natural Resources to pump water up to the top of the hill from a nearby slough. The pump, designed for firefighting, sprayed about 45000 gallons of water onto the site. Of course as they finished watering, it began raining. At least the water pump was impressive to watch. We also broadcast seeded native warm season grasses into the plots.

Planting seedlings Watering seedlings
Planting and watering seedlings; the DNR water supply equipment. top

Entering Data

Even though the plants are happily growing 500 miles away, plenty of work remains to be done at the garden. Volunteers Debra, Theresa, Art, Bill, and Jim have become excel experts as they have embarked on the task of double-entering the 560 pages of data generated this spring.

Graph of seed mass data.
This graph shows achene mass of 30 achenes from a single head, sorted by mass.
Notice that there is a clear difference between the 12 empty achenes on the left and the 18 full seeds on the right. top

Future Activities

Many exciting activities await those who are interested in continuing with or joining in the Echinacea project. The Echinacea achenes that did not germinate need to be dissected. Some seedheads collected in the summer of 2005 must still be dissected and the achenes scanned into the computer. Using these computer images, the achenes from each head need to be counted. Some seeds must still be weighed. Additionally, we will return to Minnesota in summer 2006 to measure the plants as they grow up. We will collect the seeds from plants flowering in 2006, so the process can continue next fall!

Photo of last seedling planted.
This seedling is ready to grow! top

Thanks to all the Volunteers

Chicago Botanic Garden: Art Abt, Donna Argentin, Mary Borecki, Sara Calapiz, Erin Ellis, Milton Engel, Debra Gregory-Voss, Jenny Hampton, Jan Ison, John Ison, Elaine Juhl, Emily Kay, Marita Kuhl, Jim Martin, Mary O'Conner, Theresa Paluch, Nancy Riese, Amy Schuetz, Char Schweingruber, Josh Sebor, Sue Smyczynski, Hank Southgate, Bill Wallin, and Lake Forest College undergraduates

Minnesota: John Ison, Jack Kiefer, Shelley Kiefer, Rachel Mills, Josh Sebor, Ruth Shaw, Hank Southgate, Jean Wagenius, Per Wagenius, and Sonja Wagenius-Goblirsch.

Acknowledgements:

NSF (DMS-0083468 and DEB-0545072)
Millennium Seed Bank (Royal Botanic Gardens, Kew)
Wagenius family
Minnesota Department of Natural Resources
University of Minnesota
University of Illinois at Chicago
Northwestern University
Chicago Botanic Garden

Thanks to the DNR burn & watering crew: Kevin Kotts, Wayne Anderson, Bob Moe, Rich Olsen, Jason Stroege.

Thanks to the Brian, Cathy, and the CBG greenhouse crew.

Thanks to Maggie Ingalls & Gretel Kiefer.

Thanks to all the folks who worked in the common garden in previous years--especially Helen Hangelbroek for initiating the crossing experiment in 2004.