BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Grindelia squarrosa | Curlycup Gumweed 



GENERAL BOTANICAL CHARACTERISTICS : 
Curlycup gumweed is a warm-season [17] perennial or biennial native forb
[8].  It grows 0.33 to 3.3 feet (0.1-1 m), with one to several branched
stems [14,12].  Flower heads are several to numerous.  The floral disk
is 0.6 to 2.75 inches (1.5-7 cm) wide.  The fruit is an achene [14].
Curlycup gumweed is taprooted, and develops a short, vertical rhizome.
The root system extends 6.5 feet (2 m) into the soil [1], with extensive
shallow root development [35].


RAUNKIAER LIFE FORM : 
   Geophyte


REGENERATION PROCESSES : 
Curlycup gumweed is a biennial or short-lived perennial which reproduces
by seed [12].  Seeds have a pappus [14], and are dispersed by wind.

Curlycup gumweed seeds were stratified for 10 weeks with a cold, damp
regime.  When planted, germination time was 3 days [24].


SITE CHARACTERISTICS : 
Curlycup gumweed favors dry areas, but grows on moist soils that lack
other vegetation [17].  It is most common in dry prairies, waste places,
roadsides, railroads, depleted rangelands, and abandoned croplands.  It
often forms almost pure stands [14,15,31].

Curlycup gumweed growth is poor to fair on gravel, clay, and dense clay,
and good in sandy loam, loam, and clayey loam.  It makes fair growth on
saline soils, good growth on gentle and moderate slopes, and fair growth
on steep slopes.  Optimum soil depth is 10 to 20 inches (25-50 cm) [8].

In eastern North Dakota, curlycup gumweed occurred on saltflats and in
wet lowlands where salinity ranged up to 1.3 percent [28].

Curlycup gumweed occurs at the following elevations [8,15,29]:

                   Elevation (feet)    Elevation (m)

          CO         3,500-8,500        1,067-2,590
          MT         3,200-6,700          975-2,042
          SD         3,600-5,000        1,097-1,524
          UT            5,000              1,524
          WY         3,600-8,600        1,097-2,621


SUCCESSIONAL STATUS : 
Facultative Seral Species

Curlycup gumweed is subdominant in climax prairie communities [6].  It
also occurs on disturbed sites [14].  It is highly drought resistant,
and may be abundant after dry periods [17].  However, by 1943 curlycup
gumweed in the mixed-grass prairie of Kansas showed only partial
recovery from the great drought of the 1930s [7].

In a black-tailed prairie dog town in a tallgrass prairie in
southwestern Oklahoma, prairie dogs of one colony progressively
retreated from the outside of the colony toward its center prior to
abandoning it.  Plant succession at this site was studied the summer
after the animals left.  Order of succession was apparent in concentric
rings of vegetation circumscribing a bare area at the center of the
colony.  Curlycup gumweed did not occur in the most recently abandoned
area, the colony center.  It did occur in longer-adandoned, surrounding
rings in association with annual threeawn (Aristida oligantha) and other
short grasses, forbs, and mid-sized grasses such as sideoats grama.  It
was not found in the undisturbed peripheral rings, which supported
climax tall grasses such as big bluestem [25].


SEASONAL DEVELOPMENT : 
Curlycup gumweed forms a rosette the first year.  The next summer, the
plant grows erect stems which branch considerably and produce many
flower heads [12,35].

Curlycup gumweed flowering times are [1,10,14,22,23,31]:

                    Begin         Peak           End
                  Flowering     Flowering     Flowering

     CA             July          ----        September
     CO             June         August       September
     IL             July          ----        September
     KS             July          ----        October
     MT             July         August       August
     ND             July         August       September
     WY             July         August       September
     Great Plains   July          ----          ---- 
     New England    July          ----        September

In North Dakota, curlycup gumweed began growth in May, and by the end of
May had attained 50 percent of its yearly growth [13].  Curlycup gumweed
attained maximum height in August.  The average length of flowering
period was 41 days; the median date when flowering was 95 percent
complete was September 4 [4].

Related categories for Species: Grindelia squarrosa | Curlycup Gumweed