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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
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