BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Descurainia sophia | Flixweed Tansymustard 



GENERAL BOTANICAL CHARACTERISTICS : 
Flixweed tansymustard is an introduced, cool-season, annual (or
biennial) herb [10,11].  It grows from 12 to 39 inches (30-100 cm) in
height.  Flowers grow in racemes which lengthen when in fruit; they may
grow up to one half the the total height of the plant.  Seeds are born
in linear pods or siliques which grow to 0.8-1.2 inches (2-3 cm) in
length and 0.04-0.06 inch (1-1.5 mm) in width [11].  The siliques are
divided into two cells with one or two rows of seed in each [21].  They
rupture when mature and disperse 15 to 25 uniserate seeds approximately
0.04 inch (1 mm) in length [11,21].  Flixweed tansymustard has a
slender, annual taproot [21].


RAUNKIAER LIFE FORM : 
   Therophyte


REGENERATION PROCESSES : 
Flixweed tansymustard regenerates by producing an abundance of minute
seed [21].  Seeds are mucilaginous when wet, which may facilitate
dispersal by animals or increase adherence to soil particles [12].


SITE CHARACTERISTICS : 
Flixweed tansymustard occurs on a wide variety of soil types.  It is
most abundant on dry, disturbed sites.  It is often found along
roadsides and ditches where mineral soil has been exposed [21].  It also
grows in open fields and along streambanks [5,21].  In southwestern
Utah, flixweed tansymustard is common in seepage areas and in flood
plain valleys at the ends of major washes [10].  Elevational ranges are
as follows [4]:

               3,500-10,800 ft (1,068-3,294m) in CO
               3,200-3,900 ft (976-1,190m) in MT
               2,500-8,600 ft (763-2,623m) in UT
               4,000-7,800 ft (1,220-2,379m) in WY


SUCCESSIONAL STATUS : 
Obligate Initial Community Species

Flixweed tansymustard is an early seral species which quickly invades
areas of exposed mineral soil with reduced plant cover [21].  It can
survive in dense stands for a few years if undisturbed, but is generally
replaced by cheatgrass (Bromus tectorum) or other species.  If the
flixweed tansymustard stand is trampled by livestock or severely
disturbed through other means, replacement by Russian thistle (Salsola
kali) is common [26].  In later seral stages flixweed tansymustard
competes poorly with perennial grasses and forbs.  


SEASONAL DEVELOPMENT : 
Flixweed tansymustard is an early-blooming winter annual or biennial
[10].  Flowering occurs from March through July depending on geographic
location [11]. The earliest reported blooming date in North Dakota is
June 10th, although the average earliest blooming date is July 30th [9].
Flowering occurs from May to June in western Utah [10].  Seeds are
dispersed from early to late summer [23].  Flixweed tansymustard
typically reaches 100 percent of the total annual growth by the end of
June in North Dakota [9].

Related categories for Species: Descurainia sophia | Flixweed Tansymustard