Scarlet gaura [Oenothera suffrutescens (Ser.) W.L. Wagner & Hoch][GAACO][CDFA list: B] Photographs Map of Distribution
Scented gaura or Drummond's
gaura [Oenothera xenogaura W. L. Wagner & Hoch][GAAOD][CDFA
list: B] Photographs Map
Wavy-leaved gaura [Oenothera sinuosa W. L. Wagner & Hoch][GAASI][CDFA list: B] Photographs
Map of Distribution
SYNONYMS:Complete scientific synonymy for Gaura is complex and
beyond the scope of this text.
DESCRIPTION:Noxious perennials, typically
with rhizomes that produce new plants. Gaura species can colonize
heavily grazed or disturbed sites in regions outside their natural
SEEDLINGS:scarlet gaura: Cotyledons ovate, 6-11 mm long, covered
with a few minute soft hairs on the upper surfaces. Subsequent leaves elliptic,
variably covered with soft hairs and tiny embedded glands. Margins smooth
to wavy, often folded or loosely rolled lengthwise. No description available
for scented and wavy gaura, but seedlings are probably similar
to those of scarlet gaura.
to top of page
PLANT:Stems woody at the base, typically
covered with short, stiff, flattened and long, spreading hairs. Leaves alternate,
variable, +/- sessile, decreasing in size from the base upwards.
and UNDERGROUND STRUCTURES:
FLOWERS:Flowers open near sunset and wither the following morning.
Racemes spike-like. Flowers irregular. Petals 4(3), white, clawed,
typically fading reddish. Sepals 4(3), widely spreading, 5-14
mm long, +/- deciduous. Stamens 8, with paired teeth at filament bases.
Ovaries inferior. Insect pollinated. Self-incompatible.
and SEEDS:Fruits erect, nut-like,
4-sided, +/- ovoid with a stalk-like base, do not open
to release seeds. Differences in fruit characteristics are important for species
identification. Fruit lengths given below include the base. Seeds ovoid, +/-
flat-sided, 1.5-3 mm long, smooth, reddish-brown.
HABITAT:Dry grasslands in native range, but also cultivated fields,
heavily grazed areas, disturbed sites, and waste places.
PROPAGATION/PHENOLOGY:Reproduces by seed and vegetatively by rhizomes.
The biology and ecology of these species is poorly documented.
FAVORING/DISCOURAGING SURVIVAL:Once established,
infestations can persist. Avoiding heavy disturbance or overgrazing can prevent
Gaura species from spreading.
SPECIES:Unlike scarlet, scented,
and wavy-leaved gaura, velvetweed [Gaura parviflora Douglas]
is an introduced annual with sepals 2-3.5 mm long that barely
open, petals 1.5-3 mm long, and fruits that lack a stalk-like base
and often point downwards. Velvetweed grows in cultivated fields, pastures,
disturbed sites, and riparian areas in the South Coast and San Francisco Bay
region, to 400 m (1300 ft). Gauras are closely related to Epilobium
species, such as fireweed and willowherbs. Unlike the nut-like fruits of gaura,
Epilobium species have capsules that split open from the tip
to release seeds with a tuft of white hairs at one end.
to top of page
Prevention and control:
These Gaura species are native to the Great Plains of North America, extending
from Mexico to Canada. Both Robbins (1951) and The Jepson Manual state that
Oenothera suffrutescens is native to California. However, these plants may become weedy
in certain rangeland situations. There is little information available regarding
the biology and ecology of these species. They are typically native grassland
perennial herbs, which occupy dry sites, and do not appear to be negatively
affected by grazing. The Jepson Manual describes oenothera xenogaura and Gaura
sinuata as "rhizomatous, forming dense mats," and Oenothera suffrutescens as "woody stemmed and branched below ground." These characteristics
allow these species to establish and persist in degraded range areas. Gaura
coccinea has been observed to expand its native range northward into the southern
interior grasslands of British Colombia. Continued expansion in California
where heavy overgrazing occurs is very likely.
The key to management of these species is proper land use, before they become
a problem. Avoid overgrazing dry range areas and reduce stocking rates in
areas where these plants are patchy. If possible, minimize disturbance around
patches to reduce the chances of spread.
Controlling established infestations is a very difficult task. Cultivation
is not possible in many infested areas, and may spread rootstocks to new areas.
Mowing may reduce seed production, but will not provide long-term control.
Biocontrol for these plants is not a current option. Establishing competitive
vegetation may prevent new seedlings from becoming established. However, these
species are well adapted to grasslands and can persist in competitive healthy
There are certain herbicides that will provide short term control of these
species. Glyphosate (2 quarts per acre) may be applied to actively growing
infestations. Control may be better if applied in the fall, when then plants
are actively translocating sugars to the roots. Control will be poor if plants
are drought stressed or dusty. Glyphosate is a nonselective treatment and
will injure or kill any other actively growing vegetation. Refer to the label
for rates and precautions.