Alkali sida or Alkali mallow [Malvella leprosa (Ortega) Krapov.][SIDHE][CDFA list: C] Photographs

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SYNONYMS:alkali mallow, 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

GENERAL DESCRIPTION:Low-growing perennial, 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 it.

SEEDLINGS:Cotyledons ovate to heart-shaped.

MATURE PLANT:Stems 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.

ROOTS 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:May-October. 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 head-like.

FRUITS 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.

HABITAT:Inhabits many 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.

DISTRIBUTION:Throughout California, especially the Central Valley; to Washington, Idaho, Texas, Mexico, South America. To 1000 m (3300 ft).

PROPAGATION/PHENOLOGY:Reproduces 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 disperse seed.

MANAGEMENT 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.

SIMILAR SPECIES:To 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.

Smith, D. T., A. F. Wiese and L. New. 1971. Weed control around playa lakes and tailwater pits. Consolidated Progress Report, Texas Agricultural Experiment Station. PR 3197-3209: Weed and herbicide research in West Texas 1971-73, pp. 29-31.

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