BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Artemisia absinthium | Absinth Wormwood 



GENERAL BOTANICAL CHARACTERISTICS : 
Absinth wormwood is a nonnative, long-lived, fragrant, perennial herb
that grows each year from a woody base.  An individual plant has 20 or
more stems each growing 1.3 to 4.9 feet (0.4-1.5 m) tall.  The fruit is
an achene without a pappus.  The well-developed root system consists of
a taproot occasionally reaching 2 inches (5 cm) in diameter with shallow
lateral branches extending 6 feet in all directions [18].  Absinth
wormwood may be weakly rhizomatous [14,27].  The roots lack the
interxylary bark of some Artemisia spp. which protects the roots from
dessication [15].


RAUNKIAER LIFE FORM : 
   Hemicryptophtye


REGENERATION PROCESSES : 
Absinth wormwood reproduces primarily by seed and is a prolific seed
producer [15,18,24].  Although the small seeds do not have any specific
morphological provision for dispersal, they are easily scattered in hay
and by wind, water, and animals.  The seeds retain their viability for 3
to 4 years [15].  Viable absinth wormwood seeds have been found in the
soil of undisturbed prairie grasslands in North Dakota [11].

Germination rates were measured under various pretreatment and
photoperiod conditions.  Germination was best on moist soils.  It
occurred over a wide range of temperatures between 41 and 104 degrees
Fahrenheit (5-40 deg C) [15].

Absinth wormwood invades extreme northern environments during warm
periods but may not reproduce successfully.  Absinth wormwood was
present in northeastern Manitoba in 1989 but had not produced seeds when
observed in late summer [20].

Maw and others [15] and Staniforth and Scott [20] did not find any
evidence of vegetative reproduction by absinth wormwood.  However,
Selleck and Coupland [18] suggested that absinth wormwood may regenerate
from shallow lateral root branches when plowed.  Welsh and others [27]
reported that absinth wormwood has a rhizomatous caudex, and Lym and
others [14] stated that absinth wormwood may spread by rootstock.


SITE CHARACTERISTICS : 
Absinth wormwood grows on disturbed sites such as along fencelines and
roadsides, on borrow pits and gravel piles, and on overgrazed pastures
and fields recently abandoned from cultivation [15].

Absinth wormwood grows on a variety of soils from gravels to clay loams
[15].  It grows on gravelly soils in Glacier National Park [13], and on
a cobble-gravel substratum on the upstream portion of Columbia River
islands where sand is washed away each spring during high water [8].

Absinth wormwood grows best in moist habitats.  During drought it dies
out on coarse, gravelly soils but survives in ravines and on north-facing
slopes [15,18].  

Absinth wormwood occurs from 5,000 to 7,000 feet (1,500-2,100 m)
elevation in Colorado [28].


SUCCESSIONAL STATUS : 
Absinth wormwood colonizes open, disturbed sites.  Establishment is
minimal where there is a closed grass stand [15].  Absinth wormwood
seedlings which germinated in an ungrazed stand of needle-and-thread
grass did not survive [18].

Absinthe wormwood tolerates some shade [15].  It was found growing
vigorously within a tree plantation with approximately 60 percent crown
cover [18].


SEASONAL DEVELOPMENT : 
Absinth wormwood growth begins in early spring and flowerstalks are
produced by mid-July [15].  Absinth wormwood flowers July through
September [3,15,28].  In North Dakota, absinth wormwood began flowering
the second week of August [22].  Seeds mature in early fall.  Seedlings
emerge from early spring to August whenever moisture and warmth are
available.  Rosettes form by the end of the first growing season [15].

Related categories for Species: Artemisia absinthium | Absinth Wormwood