Why our native orchids are so difficult to grow...Orchids take mycorrhizae to an extreme Orchids...

transcript

Why our native orchids are so

difficult to grow

Melissa McCormick

Smithsonian Environmental Research Center

Edgewater, Maryland

• ~ 30,000 species (10% of all

flowering plants)

• Occur on all continents

except Antarctica

• Almost 50 species in PA

• Widely threatened and

endangered

• Complex life histories

• ‘Canary in the coal mine’ of

the plant world

Orchids

Source: USDA online database

Approximately 250 species of native orchids

57% listed as threatened or endangered at the state or federal level

Orchids in North America

was fascinated by orchids’

elaborate pollination and by

why plants that produce so

many seeds are so often rare.

calculated that if all seeds

grew into plants then the great

grandchildren of a single

orchid would “cover the earth

in one continuous green

carpet”.

Charles Darwin

Accordingly, our native orchids are notoriously

difficult to grow in the garden or greenhouse

©Prem Subrahmanyam

www.planteck.com

http://www.orchid-care-tips.com

http://www.vivaiozanelli.com

A few of our native orchids

are available to

gardeners...

but most are very difficult

to keep alive for long.

https://www.flickr.com/photos/ncorchid/

Some of our most attractive native orchids aren’t

available (unless they’re wild-collected),

often because

professional

growers have

trouble growing

How are orchids different from other plants?

What does orchid research tell us?

What will it take to apply this research to native orchids in North America and find out what it takes to grow them?

Where does the North AmericanOrchid Conservation Center fit in?

What is it about orchids?

Orchid reproduction depends on

other species

Pollinators

What do fungi do for plants?

A mycorrhiza is a symbiotic association between a plant

root and a fungus

Most plants in most ecosystems

All plant families

Essential for access to nutrients and

Protect against pathogens

OrchidsMost plants

0.05mm

Ectomycorrhizae

Arbuscular mycorrhizae

Wikipedia

genetik.bio.lmu.de Kuga et al. 2015Beyrle et al. 1995

www.hardyorchidsociety.org.uk

Tulasnella violacea

Tulasnella violea

Orchid mycorrhizal fungi:

Images from J. Breitenbach “Fungi

of Switzerland” 1986

Ecologically diverse

Ectomycorrhizae,

Mycoparasites,

Pathogens,

Decomposers

Poorly-studied

Widespread and common

Morphologically indistinguishable

Orchids take mycorrhizae to an

extreme

Orchids cheat their mycorrhizal fungi.

Orchids eat their fungi.

Orchids are entirely dependent on fungi for all their

nutrition at least early in life.

This early life stage may last only a few months or

many years.

2.5 mm

Ungerminated

protocorms

1 mm1 mm

Seeds have no nutrients.

Germination requires specific fungi.

Fungi provide all nutrients, including carbon.

Fungi produce more vigorous seedlings

Orchid seeds and fungi:

Pelotons (fungal coils) in an orchid

root (Beyrle et al. 1995).

Adult orchids and fungi:

Adult Goodyera showing below-ground parts.

Fungi form pelotons in root cells.

Most orchids continue to get nutrients from fungi as adults.

Fungi help orchids tolerate stress.

(Zelmer 1994)

Canopy Thinning Experiment – Increase light

Transmitted Light (Mols / m2 / d)

4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

Change in #

2012-2

Populations with no thinning

Populations with thinning

In populations where we thinned the canopy, orchids got bigger

Adult dependence on fungi

Exposed plants of two orchid species to drought or

shade for 12 weeks.

Drought: Direct

effects on both

plant and fungus

Shade: Direct

effects on plant but

not fungus

We know fungi are important for orchids.

The fungus appears to get little out of this

relationship.

Most terrestrial orchids need specific fungi.

So, we set out to find out what we could do to

improve the fungal conditions for orchids.

How do we use this to conserve and

grow orchids?

Learning from nature

What fungi do different orchids need?

Where are those fungi?

When do the fungi support orchids?

What can we do to make the fungi grow and support orchid restoration and help grow orchids in our gardens?

Goodyera pubescens

rattlesnake plantainLiparis liliifolia

mauve twayblade

Tipularia discolor

cranefly orchid

A test with three orchids:

MD101GA243Tulasnella bifronsH

MD109MD141MD144pMD145pMD148pMD150pMD154pMD179NC245MI230NC239NC241NC244NC247NC248NC249

MD169MD186MD213-2MD219GA253Tulasnella calosporaC

Tulasnella deliquescensC

MD120MD196MD197MD191MD192MD140MD166pMI193IA233VA234IA238VA258

MD128MD170MD181MD175

MD188MD213-1

MD184MD183MD218

GA254Ceratobasidium obscurumG

Ceratobasidium cornigerumC

Ceratorhiza goodyerae-repentisC

Sistotrema brinkmaniCMD121pMD138pMD207Tomentella puniceaG

NC259Suillus cavipesG

Chroogomphus vinicolorG

Scutellospora castaneaG

Brauniella albidipesG

Gomphidius glutinosusG

Serpula himantioidesG

10 changes

McCormick et al. 2004

Different orchids need different fungi

Where are these fungi and when do

they support orchids?

There are LOTS of fungi in the soil!

Up to 150 species in 0.5g of soil.

Extract DNA from soil

2 samples 15cm apart may share only 25% of their species.

We use specific probes to look only at the DNA from the fungi we are interested in.

Fungal

Soil core

When do fungi support orchids?

Seed packets tell us when conditions are right for orchids

Host fungus distribution in 3 arrays of seed packets in Goodyera patches

West/East (cm)

When do fungi support orchids?

When they are abundant!

-100 -50 0 50 100

Patches with multiple orchids One isolated orchid

McCormick et al. submitted

leavescontrol

6 forest sites: 3 old (150+ years), 3 young (50-70 years)

36 subplots in each: 1/3 got chipped wood, 1/3 crushed

leaves, 1/3 control

What makes these fungi abundant?

Goodyera pubescensLiparis liliifoliaTipularia discolor

Seed packets of 3 species.

With and without appropriate fungi

for germination added.

What can we do to make fungi more abundant?

Tipularia discolor

P=0.003

0%10%20%30%40%50%60%70%80%90%

Decomposing

Soil With

No Wood

Tipularia only germinated in

old decomposing wood.

Liparis liliifolia

Every Liparis protocorm was from

a plot where fungi were added.

Goodyera pubescens

Rattlesnake plantain

Wood Leaves Control

tocorm

Amendment treatment

Did amendments affect host fungi and protocorm development?

P<0.001

Leaves

snella

nsity+

ControlWood

P=0.002

McCormick et al. 2012

Adding wood and leaves increased host fungus abundance and germination for Goodyera.

For Liparis, fungi were rare but could grow in lots of places.

Tipularia needed decomposing wood.

All three were limited by the abundance of the fungi they needed, but the fungi were all limited by different things.

Orchids and host fungi:

How do we use this to grow our native orchids?

Orchids persist where fungi are abundant and diverse enough to tolerate stress.

So, we need to find out what it takes to make the host fungi happy.

How do we make gardens good for orchid fungi?

It depends on the orchid and their fungi.

Many orchid fungi need decomposing wood, some need old forests, some need young forests, some need particular types of trees.

What does this mean for growing native orchids from seed and in the garden?

Make the garden resemble the natural environment

Make mature orchids less dependent on their fungi

Choose orchids that are less picky about fungi once mature

Don’t fertilize. Use untreated hardwood or leaves as mulch.

Find out what conditions the fungi need

Cypripedium parviflorumSpiranthes cernua

Hexalectris

grandiflora

Goodyera

pubescens

Platanthera

praeclara

Photos courtesy of Hal Horwitz

Hexalectris

grandiflora

Goodyera

pubescens

Platanthera

praeclara

Our mission:

Conserve our native orchid heritage

EDUCATION

• Promote collaborative research to raise botanical literacy

• Create internships, fellowships, web sites, exhibits

• Develop dynamic and interactive web presence

• Develop educational tools

CONSERVATION

• Protect habitat

• Establish regional and national seed and fungal banks representing the range of species genetic diversity

PROPAGATION

• Develop protocols for propagating native orchids

• Restore native populations

• Establish sustainable populations in private and public gardens with an initial focus on botanic gardens

our approach is collaborative

SmithsonianU.S. Botanic Garden

APHIS-USDA Kew Gardens Longwood Gardens

Michigan State University Orchid Conservation Coalition Old Dominion University

Pollinator Partnership Seeds for Success University of Florida

UC, Berkley UC, Santa Cruz US Forest Service

Virginia Native Plant Society Wabash College Wintergreen Nature Foundation

Minnesota Landscape Arboretum NatureServe

NAOCC’s first exhibit at the annualSmithsonian-US Botanic Garden show

Go Orchids websitegoorchids.northamericanorchidcenter.org

Regional groups are forming to collect seeds and fungi as well as begin

propagation efforts

Hexalectris

grandiflora

Goodyera

pubescens

Platanthera

praeclara

Join and share in our vision and mission to:

Conserve our native orchid heritage

Hexalectris

grandiflora

Goodyera

pubescens

Platanthera

praeclara

Why our native orchids are so difficult to grow...Orchids take mycorrhizae to an extreme Orchids...

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