BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Hierochloe odorata | Sweet Grass 



GENERAL BOTANICAL CHARACTERISTICS : 
Sweet grass is a native, rhizomatous perennial grass [7,12,34].
Rhizomes are slender and creeping [7,15].  Culms are hollow, erect [11],
and 8 to 24 inches (20-60 cm) tall [9,12,15,16]; they arise from among
the dead foliage of the previous year [7,22].  Cauline leaves are few
and short; leaves of sterile shoots are 4 to 12 inches (10-30 cm) long
[11,12].  The inflorescence is an open pyramidal panicle 1.6 to 4.7
inches (4-12 cm) long, with slender branches [12,15,22].  Spikelets are
three-flowered [22,34]; lemmas are awnless [7,9].  The fruit is a
caryopsis [22].  Rhizomes and roots form a dense mat beneath the soil
surface [20].


RAUNKIAER LIFE FORM : 
   Hemicryptophyte
   Geophyte


REGENERATION PROCESSES : 
Sweet grass spreads vigorously [9] by creeping rhizomes which are often
fairly deep [15,22].  It also reproduces by seed [12,22].  However,
sweetgrass is largely infertile [34]; it produces relatively few
seedheads, and these contain few seeds [20].


SITE CHARACTERISTICS : 
Sweet grass occurs in wet meadows [7,11,15,33], low prairies [22], the
edges of sloughs and marshes [11], bogs [15], shaded streambanks [10],
lakeshores [34], and cool mountain canyons [10].

Sweet grass grows on moist, heavy soil near the upper areas of the tidal
marshes around the coast of Nova Scotia [27].  It occurs on granular
calcareous soil from glacial river deposits on the Churchill River
estuary in northeastern Manitoba [26].  In northeastern Alberta,
sweet grass occurs on well-drained loamy soil with heavy clay subsoil; pH
is 4.7 near the surface and increases with depth [25].  It occurs on
coarse river gravel terraces covered by a 2-inch (5-cm) layer of organic
material (pH 6.0) along the McKinley River in south-central Alaska [32].

Sweet grass has been reported at the following elevations:

                     Feet            Meters

   Alaska          730-3,281        223-1,000  [18,32]
   Arizona           7,000            2,134    [19]
   California        6,000            1,830    [14]
   Colorado      7,500-11,500     2,286-3,505  [12]
   Utah          6,990-11,485     2,130-3,500  [34]


SUCCESSIONAL STATUS : 
Facultative Seral Species

Sweet grass is usually found in mid-successional communities.  It can
withstand some soil disturbance.

Sweet grass was a major component of the meadow zone just above high
water on the Churchill River in northeastern Manitoba.  This was the
earliest closed-cover successional community on the flats.  Sweet grass
was not present in later successional zones [26].

Sweet grass was a minor component of undisturbed and disturbed dry
grassland sites in northeastern Alberta.  Disturbance by vehicle traffic
and bison had caused soil compaction and erosion [25].

Sweet grass was a component of a wheatgrass-sedge community in
north-central Alberta which had succeeded a marsh community [23].

Sweet grass was a minor component of the meadow stage of succession on
gravel outwash terraces in south-central Alaska.  It was not present in
earlier or later stages [32].


SEASONAL DEVELOPMENT : 
In spring, creeping rhizomes of sweet grass produce inconspicuous
fruiting culms with leaves that are few and short [5].  Somewhat later,
long leaves develop from separate sterile basal off-shoots [27].  Culms
shrivel soon after flowering [7].

In southwestern Saskatchewan, sweet grass first flowered, on the
average, on June 2 (recorded over 6 years), the earliest date being May
17, and the latest June 22.  The mean number of days in flower was 28
[3].

Sweet grass is among the earliest flowering of Alaskan grasses.
Seedheads are formed in autumn and remain small and hidden through
winter in the new growing shoots, which elongate the following spring.
Seedheads appear early in May, almost as soon as the grass begins spring
growth.  Anthesis occurs near May 20, and seed is ripe from late July to
early August [20].

The following sweet grass flowering dates have been reported:

              Alaska            late May         [20]
              Arizona           June-July        [19]
              Michigan          spring           [33]
              North Dakota      May              [4,28]
              South Dakota      late April-July  [22]
              Great Plains      May-July         [11] 
              Southwestern
                United States   April            [7]
              Nova Scotia       early May        [27]
              Saskatchewan      June             [3]

Related categories for Species: Hierochloe odorata | Sweet Grass