Reproductive Biology of Cape Ivy

(Delairea odorata)in California

Ramona RobisonPlant Biology Graduate Group

UC Davis

Research Questions

• Is viable Cape ivy seed being produced in California?• If so, what are its germination requirements?• Is Cape ivy self-incompatible and does it need to

cross with another biotype?• Are there different biotypes in California?• How can this information be used for management?

Cape Ivy Reproductive Biology

• Viable (filled) seed locations

• Field and greenhouse self-compatibility experiments

• Seed biology experiments

Photograph by Jack Clark

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Cape Ivy Viable Seed

Locations2001-2004

Viable

Not Viable

Two types in California, but the stipulate type is in all but one location in South Africa

Stipulate Type(ST)

Non-Stipulate Type(NS)

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Distribution of Stipulate, Non-Stipulate,and Both Types

Stipulate

Non-Stipulate

Both Types

Locations of Field Self-Compatibility Trials2002-2003

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Marin County

Field Self-compatibility Test Results (02/03)

Location ST/NS Closed % Open %Bodega Bay NS 0 0.33Marshall ST 0 0North of Bolinas HWY1 ST 0 0Volunteer Canyon ST/NS 0.04 20Stinson Beach ST 0 0Muir Beach NS 0 0.56Rodeo Valley GGNRA ST 0 0San Francisco Presidio ST 0 0

Greenhouse Crossing Experiment (02/03)

• Performed at Bodega Marine Lab Greenhouse• Used a variety of stipulate and non-stipulate

locations

Greenhouse Crossing Experiment Results

PresidioSan Francisco

County

Bodega BaySonoma County

Toro CanyonSanta Barbara County

JennerSonoma County

Stinson Beach

Marin CountyPacifica

San Mateo County

0% 0%

ST

STNS

NS

3.8%

0.1%

3.1%Open

0% 1.5%Open

16.9%

2.5%

0%13.9%

75.3%

0%Open

NS ST

11.7%Open 14.7%

0.1%

0.1%

Field Crossing Experiment (2004)

• Performed at Volunteer Canyon Site, along Highway 1 in Marin County

• This site had 20% open pollinated seed set in 02/03 experiment and stipulate and non-stipulate plants for crossing

Field Crossing Experiment Results (2004)

StipulatePlants

Non-Stipulate Plants

Closed0%

Closed0.09%

Open6.2%

Open10.7%

Seed Biology

• Germination temperature

• Seed weight and germination

• Seed burial depth and germination

Cape Ivy Germination at a Range of Temperatures

Temperature (C)

Num

ber S

eeds

Ger

min

atin

g

Cape Ivy Seed Weight Classes

Photographs by Jack Clark

Germination of Cape Ivy Seeds in Four Weight Classes at 20ºC

0102030405060708090

Perc

ent G

erm

inat

ion

0-0.1 0.1-0.2 0.2-0.3 0.3+Weight (mg)

01020304050607080

Perc

ent G

erm

inat

ion

Surface 1 2 3 4Depth (cm)

Cape Ivy Germination at Surface and Different Depths

Sprouting of Cape Ivy Stem Fragments atDifferent Soil Depths

01020304050607080

Perc

ent N

ode

Spro

utin

g

Surface 2 4 6Burial Depth (cm)

Conclusions• Cape ivy produces viable wind-dispersed seed

throughout California

• Most populations appear to be clonal and self-incompatible

• Populations with stipulate and non-stipulate types may produce more viable seed

• Seeds need to be on the soil surface to germinate and germinate at a wide range of temperatures

• One node fragments can produce a new plant, but they must be on or close to the soil surface

Acknowledgements

Joe DiTomaso,Guy Kyser and many others

FundingUC IPM Exotics ProgramJastro ShieldsPlant Biology Block GrantBodega Marine Lab