Alkali sida or Alkali
mallow [Malvella leprosa (Ortega) Krapov.][SIDHE][CDFA list: C]
ivy-leaf sida, creeping mallow, dollar weed, white mallow, star
mallow, whiteweed, Sida hederacea (Dougl.) Torr. or Torr.
ex A. Gray, Sida leprosa (Ortega) K.Schum. var. hederacea
(Douglas ex Hook.) K.Schum., Sida obliqua Torr. &
Gray, Malva hederacea Dougl. ex Hook
to 0.4 m tall, with deep, creeping roots. Alkali
sida is a widespread native of the Western U.S. and is usually
a desirable component of natural communities. Plants typically
form colonies, especially in disturbed places. Extensive colonies
can be troublesome in agronomic crops, orchards, and pastures.
Alkali sida can be toxic to sheep (and possibly
other livestock) when consumed in quantity by forming hairball
blockages in the intestines. However, animals usually avoid grazing
ovate to heart-shaped.
erect to prostrate with tips +/- erect (decumbent), densely
covered with minute, whitish, bristly and scale-like star-shaped
hairs. Leaves alternate, fan- or kidney-shaped to +/-
triangular, 1.5- 4.5 cm wide, typically asymmetric with oblique
leaf bases, often appear corrugated. Surfaces, especially
lower, covered with minute, whitish star-shaped hairs. Margins
blunt-toothed, +/- wavy. Petioles ~1-3 cm long.
and UNDERGROUND STRUCTURES:Vertical roots deep (> 46 cm). Horizontal
roots long, creeping, ~ 15-20 cm below the soil surface,
produce new shoots. Fragmented roots can generate new plants.
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Flowers axillary, solitary or in small clusters, 2.5-3.5 cm in
diameter, on stalks ~1-3 cm long. Bractlets below flowers 1-3,
linear, ~ 3 mm long, +/- deciduous. Petals 5, cream-colored
to pale yellow, 10-15 mm long, covered with star-shaped
hairs in bud. Stamens numerous, with filaments fused into a tube.
Filament tube fused to petal bases. Ovary chambers 6-10. Stigmas
and SEEDS:Fruits (schizocarps) disc-shaped, 5-8 mm
in diameter, separate into 6-10 triangular segments (mericarps).
Segments dark brown, ~ 3 mm long, reticulate on the sides, 1-seeded,
do not open to release the kidney-shaped seed.
plant communities in semi-arid to arid regions, but also orchards,
vineyards, agronomic crops, especially grains and cotton, pastures,
roadsides, landscaped areas, and gardens. Often grows on moist,
alkaline to saline soils.
California, especially the Central Valley; to Washington, Idaho,
Texas, Mexico, South America. To 1000 m (3300 ft).
by seed and vegetatively from
creeping roots. Seed germinates in spring. Seedlings grow
rapidly and flower the first year. Foliage dies back in fall,
and new shoots emerge from roots in spring. Water can effectively
FAVORING/DISCOURAGING SURVIVAL:Heavy grazing can enhance colonization of alkali
sida by removing competing vegetation. Cultivation may facilitate
spread of plants by dispersing root fragments. However, repeated
cultivation can control or eliminate troublesome colonies.
review similarities and differences of selected species in the mallow family,
refer to the table Comparison of mallows in the appendix. Arrowleaf
sida [Sida rhombifolia L.][SIDRH] is an uncommon summer annual
(to +/- woody perennial in tropical regions) to 1 m tall, with yellow to
white flowers. Unlike alkali mallow, arrowleaf sida lacks bractlets
below flowers and has diamond-shaped to narrowly oblong or ovate leaves
2-7 cm long and 1-3 cm wide, with toothed margins. It inhabits disturbed sites
and fields in the Central Valley, to 300 m (~ 1000 ft). Arrowleaf sida
reproduces only by seed and is considered a noxious agricultural and pasture
weed in some regions of Australia. The barbed seeds can irritate digestive tract
tissues and woody stems may form indigestible masses when consumed by livestock.
Native to tropical regions worldwide.
Prevention and control: Alkali mallow is native to California,
but has been occasionally problematic forming large colonies in orchards, pastures
and some agronomic crops. Additionally, the plant may be toxic to sheep if forced
to graze heavily infested areas. The plant normally responds positively to heavy
grazing as animals generally avoid it. Repeated cultivation
may be effective at reducing infestations, but may also spread root fragments
to new areas. There is little information available for control of this plant.
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