Tarragon has been observed before and after 2 prescribed burns and 1 natural
fire [28,37,68]. Four years after a prescribed summer burn in western North
Dakota, the frequency of tarragon was nearly 3 times that found in an adjacent
unburned area. It was speculated that the increase was due to a reduction in interference
of other species following the fire and the species' ability to inhabit disturbed sandy soils and
roadsides [28].
On Hightower Mountain in western Colorado, tarragon experienced a 90%
reduction in population 2 years following a prescribed burn. Composition of the
population dropped from 0.11% to 0.01% [68]. In
Los Alamos, New Mexico, tarragon constituted 0.14% actual cover and 0.30%
relative cover in an area that had burned in 1960. After the 1977 La Mesa fire,
studies conducted to determine long-term vegetative impacts found no tarragon 1,
8, or 16 years after the fire [37].
The following description of tarragon has been compiled from the following
sources unless otherwise noted [1,2,7,20,41,42,45,46,62,64,79,89,116,124,127]. This description provides
characteristics that may be relevant to fire ecology, and is not meant for
identification. Keys for identifying tarragon are available
[2,7,42,45,62,124].
Tarragon is a woody, native perennial shrub with stem heights
ranging from 15.7 to 59.1 inches (40-150 cm). Aerial stems arise from thick,
horizontal rhizomes growing in clusters and singly. Leaves are alternate, 0.5 to 3.1 inches long (1.2-8.0 cm),
and 0.04 to 0.24 inch (1-6 mm) wide.
Basal leaves are cleft with 1 to 3 lobes. The inflorescence is a panicle with
numerous flowers. Outer florets are pistillate and fertile,
central flowers are sterile, and ovaries are abortive. The seeds are achenes.
Seed size is approximately 0.06 inch (1.5 mm) in length.
Tarragon supports large numbers of adventitious roots containing interxylary
cork (formed within xylem tissue), offering the plant protection in xeric habitats [89]. One individual in
Los Alamos, New Mexico was found to have a rooting depth of 83.9 inches (213 cm)
[38]. Tarragon forms associations with vesicular-arbuscular mycorrhizae
[96].
Extracts derived from leaf material of tarragon displayed various effects on the
germination of 18 species. Growth was inhibited in field pennycress (Thlaspi arvense),
lacy tansyaster (Haplopappus spinulosus), and largebracted plantain (Plantago patagonica) while
growth in needle-and-thread grass was enhanced [59]. Treatments of a 2,4-D,
diesel oil mixture applied to control little spikemoss (Selaginella
densa) on rangeland resulted in a 90%-95%
reduction in tarragon density [106].
In western Colorado, the effects of spraying, burning, and chaining were
evaluated for their effectiveness in increasing forage for deer, elk,
and cattle. Although none of the treatments were significantly different
(P<0.05) with effect to tarragon production, spraying reduced percent composition from
0.46%-0.01%, burning from 0.11%-0.01%, and chaining increased percent composition
from 0.00%-0.01% [68].
Tarragon is one species of sagebrush which is fed upon in small amounts by
the sagebrush grasshopper (Melanoplus bowditchi) [97]. In
semiarid mountain ecosystems, the presence of ant mounds was positively correlated (p less than 0.01)
to the occurrence of tarragon within a 3m radius of the mound [18].
Tarragon reproduces both sexually and vegetatively [27]. Vegetative reproduction is from rhizomes [116,123].
Breeding system:
Population outcrossing has been documented for sagebrush species [80].
Pollination:
Sagebrush species are wind and self-pollinated [80], with insect-assisted pollination likely [120].
Seed production:
When grown for culinary or medicinal purposes, it is reported that tarragon rarely produces seed [112].
When grown hydroponically, tarragon was reported to produce no seed at all
[1].
Seed dispersal:
Artemisia species are not able to disperse seeds far from the
mother plant [120].
Seed banking:
No information is available on this topic.
Germination:
Commercially grown tarragon requires 10 to 14 days to germinate. Germination is dependant upon soil
characteristics and weather conditions [131].
Seedling establishment/growth:
No information is available on this topic.
Asexual regeneration:
Tarragon regeneration is most commonly a result of rhizome sprouts [116,123].
Tarragon grows in the pine-oak (Pinus-Quercus spp.) woodlands on shaded slopes of the Rincon
Mountains in Arizona [10]. In Utah, tarragon is recognized as a weedy plant species due to its
ability to colonize disturbed sites [96]. In southeastern North Dakota, tarragon is considered a pioneer, transitional,
and climax species with greatest frequency and cover as a climax species and the
least as a pioneer species [16].
On a subalpine Earth flow that occurred in Colorado around 1923, tarragon
was characteristic of both flow and slump areas during the 7-year period in
which vegetation studies were being conducted (1947-1954, with the exception of
1953). It occupied both areas of disturbance with equal density and was
important in both floodplain and xeric site revegetation [73].
Tarragon is difficult to root [1] and does not establish well from seed.
In southeastern Montana, tarragon was examined for future land reclamation
possibilities on sites disturbed by coal mines. Hand-stripping the seed was
necessary and optimum germination was obtained from 12 month old seed exposed to
68 ºF (20 ºC) temperatures without light or by alternating
light with 68 ºF to 77 ºF (20º-25 ºC) temperatures. This study determined that there
was no optimal planting time[33].
In western North Dakota, tarragon made up 28% of the species found in unbrowsed
plains grasslands bordering active mining sites, indicating a potential source for seed
when reclaiming surface mine sites [63]. It has been suggested that tarragon
also be investigated for its ability to regenerate salt desert shrub ranges [99].
