BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Artemisia ludoviciana | Louisiana Sagewort 



GENERAL BOTANICAL CHARACTERISTICS : 
Louisiana sagewort is a long-lived, fast growing, native, aromatic,
suffruticose, perennial forb typically ranging in height from 11.7 to 39
inches (3 to 10 dm) [5,8,16].  Plants spread by rhizomes; stems are
usually solitary or loosely clustered.  This species exhibits wide
ecotypic variation in stem height, leaf color and shape, seed
production, and degree of rhizomatous spread [24].  Generally, alpine
forms are somewhat more decumbent than the more erect, low elevation
forms.  Louisiana sagewort is extremely drought and cold tolerant.
Although most plants die back to woody stem bases following frost, some
forms are able to maintain green, basal rosettes until late winter,
while other forms produce an abundance of fall sprouts [26].  The root
system is quite extensive and consists of a coarse root mass located 1
to 4 inches (3 to 10 cm) below the soil surface.  Nitrogen-fixing root
nodules have been reported for this species; however, nodulation is
somewhat inconsistent [7].  Stranathan and Mosen [26] indicate that
Louisiana sagewort improves soil fertility and tilth.


RAUNKIAER LIFE FORM : 
   Chamaephyte


REGENERATION PROCESSES : 
Louisiana sagewort employs both sexual and vegetative reproductive
strategies.  Numerous, wind-dispersed achenes are produced in the fall.
Although seed production varies widely among ecotypes, most plants
produce abundant seed from flowers which are either open or
self-pollinated.  Seeds are very small (approximately 3,800,000 per
pound [8,360,000/kg]).  Germination rate is often only 30 to 40 percent
at purities of over 90 percent [26].  Most seed is dispersed within the
first 7 days of seed maturity [9].  Seed heads mature quickly and
shatter easily.  Viability declines after more than 2 to 3 years in
storage.  Harvey [9] reported optimum germination temperatures of 70 to
73 degrees Fahrenheit (20-23 deg C), the highest optimum range of four
Artemisia species compared.  He suggested that this range may be an
ecological adaptation to protect newly emerged seedlings from frost
damage on lowland sites in Montana.  Seedling mortality is quite high in
nature, despite relatively rapid root elongation.  Mean survival of
seedlings on Montana study sites was approximately 1.2 percent.  Data
indicate that survival per 1,000 seedlings was only 0.07 percent.
Plants produce seed within 3 years following establishment.  Stranathan
and Monsen [26] reported that plants produced seed within two growing
seasons on irrigated seed plantations in Colorado.

Louisiana sagewort regenerates vegetatively via rhizomes.  The extensive
root system is generally a dense, coarse root mass located from 1 to 4
inches (3 to 10 cm) below the soil surface.  Harvey [6] reports sagewort
colonies reaching diameters of 50 feet (15 m) on lowland sites in
Montana, with annual radial increases averaging approximately 1.2 inches
(3 cm).  Efforts at age determination on these sites suggested larger
colonies approaching 200 years of age or more.  Research involving
cultivar development in Louisiana sagewort indicates that rhizome
expression is highly variable among ecotypes; some accessions are highly
rhizomatous while others exhibit almost no evidence of rhizome
initiation [9].  An accession selected for cultivar release spread
approximately 78 inches (200 cm) within 5 years following planting on
steep, unstble slopes in Colorado.  On disturbed sites in Idaho,
sprigged plants produced abundant rhizomes and fibrous roots during the
1st year [8].


SITE CHARACTERISTICS : 
Louisiana sagewort has a wide ecological amplitude and is able to occupy
a diversity of sites throughout the western United States.  Plants
typically occur scattered on dry, open sites within grassland,
shrubland, and forested communities.  Although populations inhabit sites
ranging in elevation from less than 3,000 feet (900 m) to more than
10,000 feet (3,000 m), subspecies gererally occupy rather distinct
elevational regions.  Artemisia ludoviciana ssp. ludoviciana is the most
abundant and widespread; A. l. spp. incompta is restricted to alpine
areas.  Louisiana sagewort is adapted to a wide range of soil conditions
including heavy clays, sterile sands, and granitics.  Productive sites
in Montana are often along lowland, cold air drainages; colonal
increases appear to be more rapid on mesic sites [9].

Elevational ranges for several western states are as follows [5].

	     3,500 to 11,300 ft (1,067 to 3,455 m) in CO
	     2,300 to 9,200 ft (701 to 2,805 m) in MT
	     4,000 to 11,500 ft (1,220 to 3,506 m) in UT
             3,600 to 10,900 ft (1,098 to 3,323 m) in WY


SUCCESSIONAL STATUS : 
Facultative Seral Species

Louisiana sagewort is a pioneer species that rapidly invades disturbed
sites in a variety of plant communities.  These long-lived plants
establish during early seral conditions and coexist with later arriving
species, often persisting through a wide range of successional stages.
Although frequencies are typically low on most sites, densities increase
where disturbance results in reduced species competition.  Louisiana
sagewort serves as a nurse shrub; grasses invaded plantings within 2 to
5 years on sites in Colorado [26].  As succession proceeds, sagewort
densities gradually diminish; however, remnant plants will reemerge to
occupy vegetative openings.


SEASONAL DEVELOPMENT : 
Phenological development in Louisiana sagewort has not been well
documented.  Detailed data from Montana for sites below 5,900 feet
(1,800 m) are presented below.  In general, plants above this
elevation developed 2 to 3 weeks later [9].
 
Phenological stage                  Month
apical bud enlargement              early to mid-April
apical twig elongation              mid-April to mid-May 
apical growth ceases (vegetative)   mid-May to early-June
floral branch elongation            June
floral buds enlarging               July
anther development (buds yellow)    early to mid-August
anthesis                            mid-August to mid-September
cypsella (fruit) development        mid-September to mid-October
dissemination initiated             mid-October to early November
dissemination completed             mid-November to mid-December
winter dormancy                     mid-December to March

Related categories for Species: Artemisia ludoviciana | Louisiana Sagewort