California Plants and Fire. |
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There are decades of conflicting information about the flammability of native plants. The fear of fire and the abundance of misinformation about native plants has resulted in wildlands (and their wildlife) being replaced with more flammable landscape materials. After 30 years of experience with California native plants in their natural environment, (and fourteen years as a firefighter) we have developed a simple method to compare the flammability of native plants. The experiment is simple, fair, and repeatable, with relevance for firefighters, designers, and homeowners. In a two week period of September of 2005, temperatures were in the 90's and the humidity was about 30%. Leaves (or clusters as they were on stem) of various plant species were tested for ignition times until two numbers were the same within a few seconds. If after five tries(boring!), numbers were still divergent, numbers were either listed as a range or averaged if all over the place. Most plants tested were field grown and had not been watered all summer (exceptions noted in table below). Every effort was made to duplicate (or worse) a dry coastal garden under water rationing. Garden watered plants should be considerably harder to ignite if watered as little as fifteen minutes once every two weeks, BUT, not always. However, the worst fires I've seen are at the end of a drought cycle when there is no water to even fight the fire, never mind water the plants. (For those of you back east, it is similar to putting the plant in a convection oven set at 130 degrees for a month.)
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If you live in town and have a twenty foot front yard, ignore this list. This is primarily for those of you in rural residential areas, at the worst with a poor well, thirty minutes from the nearest fire engine and are gone a lot. The designers that are planning an urban interface should find this useful also. Using a propane torch with a one centimeter length flame (+/-
1mm), the blue tip of flame was placed on to a leaf, if leaves
large, or first leaf cluster if leaves small, until the leaves
ignited and held a flame longer than five seconds. Some leaves
would flash. If they held a flame or carried to other leaves that
was counted. Some blacked and never ignited, some never even
glowed, and others ignited easily. At first the tests were done on
the plants themselves, but that proved too exciting and the
slightest breeze altered the results (and had potential for even
more excitement). I settled on collecting a few stems of a few
plants and testing those in a closed barn within minutes of
collection. Results were not what I'd had heard or read, and often
not what I expected. Generally, (and boy are there
inconsistencies,) the more drought tolerant the plant, the poorer
it burns, the smaller the leaf, the poorer it burns, and the wider
spaced leaves are very hard to ignite. For the most part,
un-watered natives did better than watered non-natives. This experiment really points out that weed control and garden hygiene are as important, or more important, than plant choice or irrigation practices. |
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Genus |
Species |
Variety |
Cultivar |
live ignition (seconds) |
dead leaf ignition (seconds) |
notes |
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bracteata |
>60 |
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greggii |
>60 |
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one weak flash |
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circinatum |
15 |
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macrophyllum |
>60 |
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negundo |
californicum |
30 |
1 |
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millefolium |
californica |
5 |
1 |
six inch flame height |
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millefolium |
rosea |
Island Pink |
>60 |
1 |
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fasciculatum |
30 |
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dried seed heads -1 second. |
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jordanii |
>60 |
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californica |
>60 |
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pallens |
>60 |
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a lot of dead grass, but the green leaves extinguished the dead ones |
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rhombifolia |
15 |
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psilostachya |
>60 |
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margaritacea |
>60 |
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californica |
>60 |
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leaves develop water blisters |
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eximia |
no fuel |
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formosa |
no fuel |
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pubescens |
no fuel |
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shockleyi |
no fuel |
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menziesii |
>60 |
15 |
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Manzanitas are all over the chart and do not appear to change when watered. |
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Baby Bear Manzanita Bush |
>60 |
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Ian Bush Manzanita |
10 |
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watered ones were also 10 |
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John Dourley |
45 |
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watered sample |
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Mama Bear Manzanita |
7 |
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Margarita Pearl |
30 |
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Pacific Mist |
30 |
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densiflora |
Harmony Manzanita |
>60 |
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densiflora |
Howard McMinn Manzanita |
15 |
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watered sample was 30 |
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densiflora |
Sentinel Manzanita |
>60 |
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edmundsii |
Big Sur Manzanita |
20 |
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edmundsii |
Carmel Sur Manzanita |
30 |
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glandulosa |
adamsii |
5 |
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glandulosa |
glandulosa |
10 |
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glandulosa |
howellii |
10-20 |
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glandulosa |
ssp.crassifolia |
Del Mar Manzanita |
>60 |
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glandulosa |
zacaensis |
San Marcos Manzanita |
10 |
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glauca |
20 |
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glauca |
Ramona Manzanita |
50 |
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hookeri |
Wayside Manzanita |
>60 |
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watered sample |
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hookeri |
franciscana |
Franciscana Manzanita |
7 |
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extreme drought -7 secs. watered- 7 secs., but it sure looks better |
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hookerii X pajaroensis |
Sunset Manzanita |
>60 |
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insularis |
7 |
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manzanita |
Dr. Hurd Manzanita Tree |
15 |
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manzanita |
Real manzanita |
>60 |
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watered sample |
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manzanita_x_densiflora |
Austin Griffiths Manzanita |
45 |
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watered plants easier to ignite than dry land ones? |
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mariposa |
>60 |
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even charcoal wouldn't ignite after 90 secs. |
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morroensis |
Park View Manzanita |
12 |
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obispoensis |
San Luis Obispo Manzanita |
15 |
3 |
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pajaroensis |
Paradise Manzanita |
7 |
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parryana |
Snow Lodge Manzanita |
20 |
1 |
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patula |
12 |
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pechoensis |
5 |
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pilosula |
pilosula |
Atascadero Manzanita |
5 |
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pungens |
30 |
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purissima |
Burton Mesa Groundcover |
15 |
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refugioensis |
Refugio Manzanita |
15 |
1 |
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rudis |
7 |
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silvicola |
Ghostly Manzanita |
12 |
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standfordiana |
10 |
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stanfordiana |
bakeri |
Louis Edmunds Manzanita |
15 |
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uva-ursi |
Point Reyes Manzanita |
>60 |
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watered sample |
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uva-ursi |
Radiant Manzanita |
15 |
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watered sample |
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uva-ursi |
suborbiculata |
San Bruno |
>60 |
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watered sample |
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viridissima |
>60 |
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viscida |
ssp. viscida |
15 |
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regularly watered sample- 15 secs. |
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wellsii |
Wells Manzanita |
20 |
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munita |
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californica |
Sierra Giant Pipe Vine |
>60 |
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californica |
>60 |
1 |
'melted' down to dead/dry leaves then burned after 60 secs. |
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californica |
Canyon Gray |
Canyon Grey |
>60 |
1 |
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californicaX |
Montara |
Montara |
>60 |
1 |
dead material difficult to extinguish |
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douglasiana |
15 |
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ludoviciana |
ludoviciana |
>60 |
10 |
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tridentata |
>60 |
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watered sample - >60 secs. |
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eriocarpa |
>60 |
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fascicularis |
>60 |
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speciosa |
55 |
3 |
no flame after 5 secs., had to work to light |
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ascendens |
>60 |
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one ignited at 45 secs. |
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canescens |
>60 |
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lentiformis |
Breweri |
>60 |
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douglasii |
>60 |
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will not sustain flame |
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pilularis |
consanguinea |
25 |
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varied from 12 to >60 secs. on very old plant |
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pilularis |
pilularis |
Pigeon Point |
>60 |
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used dry, unwatered plant |
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pilularis |
pilularis |
Santa Ana |
>60 |
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pilularis |
pilularis |
Twin Peaks |
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viminea |
>60 |
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californica |
>60 |
1 |
if leaves clustered, can be burnt |
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eriophylla |
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occidentalis |
>60 |
>60 |
will not stay lit |
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cheiranthifolia |
ssp. suffruticosa |
>60 |
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Carex |
globosa |
>60 |
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praegracilis |
15 |
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summer deciduous |
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sartwelliana |
>60 |
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spissa |
>60 |
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californica |
>50 |
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one in four tries was able to get leaf to burn |
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Ceanothus species are relatively hard to burn and respond well to light overhead watering once every two weeks. A dust- off once every two weeks makes them really hard to burn. |
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Blue Jeans |
>60 |
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Celestial Blue |
>60 |
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Concha |
>60 |
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Frosty Blue |
30 |
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very drought stressed watered sample = >60 |
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Joyce Coulter |
>60 |
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Julia Phelps |
>60 |
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L.T.Blue |
>60 |
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sparse foliage difficult to light |
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Mills Glory |
45 |
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>60 |
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Mountain Haze |
>60 |
15 |
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Ray Hartman |
>60 |
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Remote Blue Ceanothus |
>60 |
2 |
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Tassajara Blue Ceanothus |
45 |
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watered sample |
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Wheeler Canyon |
>>60 |
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arboreus |
20 |
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watered sample = >60 |
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arboreus |
Owlswood Blue |
>60 |
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melted leaves will not ignite |
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crassifolius |
15 |
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cuneatus |
25 |
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cuneatus |
Sierra mt. lilac |
50 |
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cyaneus |
>60 |
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cyaneus |
Sierra Blue Ceanothus |
10-30 |
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leaves roll and ignite |
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gloriosus |
Hearts Desire |
>60 |
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gloriosus |
porrectus |
>60 |
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griseus |
horizontalis |
Yankee Point |
>60 |
50 |
looked like it would burn |
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hearstiorum |
>15 |
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with regular watering = >60 |
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impressus |
impressus |
50 |
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flame held just 5 secs. on unwatered plant |
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impressus |
nipomoensis |
>60 |
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maritimus |
30 |
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megacarpusX |
Tranquil Margarita |
55 |
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oliganthus |
oliganthus |
>60 |
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prostratus |
>60 |
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ramulosus |
fascicularis |
7 |
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rigidus |
Snowball |
>60 |
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sorediatus |
Klamath |
>60 |
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spinosus |
>90 |
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thyrsiflorus |
Big Sur California lilac |
>60 |
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thyrsiflorus |
Skylark |
>60 |
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thyrsiflorus |
repens |
>60 |
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tomentosus |
>60 |
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one leaf burnt out of six |
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verrucosus |
75 |
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kept getting just over 60 secs. |
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occidentalis |
californica |
40 |
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watered sample = >60 |
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floridum |
>60 |
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occidentalis |
>60 |
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alnifolius |
>60 |
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did light once in six tries |
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betuloides |
50 |
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mostly >60 secs., some ignition |
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foliolosa |
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linearis |
>60 |
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nauseosus |
>60 |
10 |
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ligusticifolia |
>60 |
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diversifolia |
15 |
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leaves rolled and ignited |
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filaginifolia |
>60 |
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glabrata |
15 |
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stolonifera |
7 |
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cornuta |
californica |
10 |
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only lights 50% of time, vaporizes then |
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douglasii |
>60 |
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forbesii |
>60 |
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nevadensis |
15 |
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rigida |
>60 |
1 |
prune to ground every 3-5 years |
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aurantiacus |
Sierra monkey flower |
>60 |
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watered sample |
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aurantiacus |
australis |
Ramona |
>60 |
deciduous, 5 |
need to tidy! |
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aurantiacus |
lompocensis |
Vandenberg Monkey Flower |
30 |
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old flower/capsules burn |
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grandiflorus |
3 |
1 |
need to tidy! |
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longiflorus |
>60 |
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at water's edge |
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longiflorus |
Conejo monkey flower |
3 |
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seed capsules ignite watered and trimmed sample = >60 |
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puniceus |
Otay monkey flower |
3 |
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dead-heading would fix |
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rutilus |
>60 |
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water sample |
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pulverulenta |
3 |
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condensatus |
>60 |
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californica |
>60 |
1 |
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farinosa |
>60 |
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angustifolium |
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gigantea |
45 |
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arborescens |
>60 |
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ericoides |
>60 |
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Wayne Roderick Daisy |
>60 |
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glaucus |
>60 |
1 |
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glaucus |
Cape Sebastian |
>60 |
1 |
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angustifolium (californicum) |
40- >60 |
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very variable |
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crassifolium |
20 |
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tomentosum |
20 |
5 |
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arborescens |
>60 |
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foliage was non-flammable |
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fasciculatum |
foliolosum |
>60 |
1 |
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fasciculatum |
polifolium |
>60 |
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similar to lavender |
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giganteum |
>60 |
>60 |
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grande |
rubescens |
>60 |
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parvifolium |
>60 |
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umbellatum |
10 |
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dead leaves are a problem |
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umbellatum |
polyanthum |
Shasta Buckwheat |
50 |
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turns to charcoal and burns |
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wrighti |
subscaposum |
>60 |
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confertiflorum |
2 |
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took 3 tries to carry flame |
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staechadifolium |
artemisiaefolium |
>60 |
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paradoxa |
>60 |
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acanthodes |
cholla |
3 |
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spines burn good! |
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californica |
>60 |
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nothing left after 20 secs. |
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chiloensis |
>60 |
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occasionally lit, but no live coals |
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dipetala |
10 |
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latifolia X velutina |
>60 |
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Ken Taylor |
20 |
15 |
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Pacific Sunset |
15 |
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californicum |
>60 |
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californicum |
decumbens |
>60 |
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elliptica |
James Roof |
15 |
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flavescens |
pallida |
20 |
3 |
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veatchii |
15 |
3 |
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