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Re: Black gamma grass

Joan-
   Plant 1/2", seeds need darkness to germinate.  Germination rates tend to
be low.
Intolerant of shade and best in well drained soils- sandy, gravely or or
sandy loam.
Seed good for 3-4 years. Got the following from the Fire Efects Information
System Database on the web,  Sorry about the length....but hope it helps you
Caron  z5ish 8,000' on the side of Pikes Peak Colorado.

GENERAL BOTANICAL CHARACTERISTICS :
Black grama is a native, branching, warm-season tufted perennial
[8,27,28].  This drought-tolerant shortgrass exhibits a somewhat
variable growth form.  Black grama grows from 10 to 28 inches (2.5-7 dm)
in height [8].  Height varies according to grazing strategy, with black
grama averaging 13.7 inches (34.7 cm) in height under conservative
grazing and 14.6 inches (37.0 cm) on ungrazed ranges [23].  Black grama
is relatively long-lived, particularly on ungrazed ranges.  Individual
plants have survived for up to 14 years [7].

Black grama grows from a hard, knotty base, becomes stoloniferous at
lower nodes, and produces tufts of culms [8].  Solid, slender culms are
densely white-woolly, spreading, and stoloniferous to ascending
[8,14,27].  The culms remain green up to the second node from the top
during some winters [15,23].  Some respiration occurs, with a probable
decline in stored carbohydrates [15].  Clusters of leaves emerge from
the nodes during the following spring [23].

Blades are flat, flexuous, pointed, and narrow (1-5 inches [2.54-12.7
cm] in length) [23,27].  Leaves are mostly basal, twisted and involute
near the tip, hairy above, and smooth below [8,27].  Sheaths are striate
and glabrous [8].  Black grama has finely divided, well-developed roots
which are confined mainly to the upper 10 inches (25.4 cm) of soil [4].

Inflorescences are borne on one to six slender, persistent branches and
have numerous spikelets [14].  Seedheads are described as open and
flaglike [23].  Production of floral stalks varies greatly according to
precipitation received [6].  During moister years, two periods of
flowering may occur within a single year, but this is rare [6].  Black
grama also spreads through stolons which require several favorable
growing seasons for establishment, and tillering or lateral spread
[27,28].

Ungrazed black grama forms uneven stands of large tufts [23].  Ungrazed
stands are characterized by smaller, more evenly distributed plants
[23].  On extremely dry sites, black grama is described as "essentially
a bunchgrass" [6].


RAUNKIAER LIFE FORM :
   Hemicryptophyte
   Geophyte


REGENERATION PROCESSES :
Black grama regenerates through seed, stolons, and lateral spread or
tillering.

Seed production varies widely according to precipitation levels.  During
drought years very little if any flowers and seed are produced [28].  In
very favorable years, however, black grama can sometimes flower twice in
a single year [23].  An uneven distribution of precipitation during the
summer may prevent black grama seed from maturing [23].  Viability of
black grama seed is poor [27].  During a 10-year period in southwestern
New Mexico, germination ranged from 0 to 40.7 percent [23].  Campbell
and Bomberger [4] reported an average germination of 3.72 percent at a
New Mexico site.

Regeneration by stolons is a slow but important method of reproduction,
particularly during years with aboveaverage summer precipitation [4].
Stems grow from knotty bases, becoming stoloniferous when the lower
nodes root and grow into new tufts [8].  Two favorable growing seasons
are required for stolon formation and establishment [28].  One year is
required for the establishment of new sets, and a second season is
needed for the sets to become rooted and established as individual
plants [28].  One to nine stolons are produced per plant [28].
Trampling by livestock can damage stolons, and even under conservative
grazing, stolon production is much less important than tillering as a
regenerative strategy [28].  However, regeneration through stolons can
still occur during favorable years on conservatively grazed ranges when
some flower stalks remain [23].  When a range is overgrazed year after
year, stolon production is virtually nil.

Tillering is believed to be the principal means of regeneration in black
grama [4].  In favorable years tillering can produce an increase in tuft
area of up to 190 percent [4].  On ungrazed ranges black grama forms
uneven stands of large tufts which die in the center during droughts,
forming many smaller tufts [23].  When more favorable conditions
prevail, these smaller tufts enlarge through lateral spreading and can
again grow together [23].

The amount of tillering which occurs depends on the plant's vigor during
the previous year [28].  Under conservative grazing, regeneration by
tillering is most effective [28].  With overgrazing, however, no
tillering occurs [28].  Repeated cropping of black grama to 2 inches (5
cm) may prevent lateral extension [6].


SITE CHARACTERISTICS :
Black grama is widely distributed in desert grassland communities on
dry, rocky hills and uplands and on lower elevation mesas [8,27].  It
typically occurs with dropseeds (Sporobolus spp.), threeawns (Aristida
spp.), broom snakeweed, mesquite (Prosopis glandulosa), and yucca (Yucca
spp.), or in nearly pure stands [4,15,27].

It is capable of surviving on harsh sites characterized by little
rainfall, high temperatures, high evaporation, and strong winds [23].
Black grama occurs on well-drained sandy or gravelly soils [23].  It is
most commonly associated with soils high in nitrate, potassium and/or
organic matter [24].  Most soils at black grama sites in an Arizona
study had a relatively high pH or lime content [24].  Optimal soil depth
ranges from 10 to 20 inches (25.4-51cm) [9].  Roots typically grow
longer in deeper soils, making the plant more susceptible to
drought-induced injury [15].  Black grama is less affected by drought on
shallow sandy soils [15].

Black grama is generally thought to be relatively tolerant of drought,
although some authorities report a decrease following dry years [15].
During drought large tufts break up and form numerous smaller clumps
[23].

Black grama grows from 3,000 to 7,000 feet (915-2,135 m), but it most
typically occurs from 3,500 to 5,500 feet (1,068-1,678 m) [23].  It has
been reported between 4,000 and 4,800 feet (1,220-1,464 m) in Colorado
[8].


SUCCESSIONAL STATUS :
Facultative Seral Species

Black grama is a climax species in a number of desert grassland habitat
types.  Depending on the type and severity of disturbance, it can also
be part of some early seral communities.


SEASONAL DEVELOPMENT :
Growth of black grama begins as soon as adequate moisture becomes
available, generally in July [27].  The growth period usually lasts from
July to October but is primarily determined by temperature and
precipitation [23].  In extremely favorable years, two periods of
flowering may take place [23], although sometimes in years of very
severe drought no flowering or growth occurs [6].  Growth typically
began somewhat later on clipped plots in a New Mexico study [6].

Flowering generally occurs from June or July through August [8].
Fruiting usually takes place in late September, with seed dissemination
in October and November [23].

The vigor of black grama plants for a given season is largely determined
by the amount of precipitation received during the previous summer [15].
In a New Mexico study current seasonal rainfall was found to have no
significant effect on the amount of cover of black grama [6].

The stems of black grama often remain green to the second node during
the winter months [15,23].  Leaves then emerge at the nodes in the
spring [5]..


Joan Maffei wrote:

> This is somewhat off-topic, but could anyone give me some info re:
> description (esp. how tall) and culture for this grass?  I want to use it
> in an urban wildscape garden as a specimen plant.
> Thanks in advance for your help,
> Joan Maffei
>
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