Print Report

A0798 Pluchea sericea Wet Shrubland Alliance

Type Concept Sentence: Pluchea sericea is dominant or codominant in an open to continuous shrub layer with Allenrolfea occidentalis, Atriplex canescens, Atriplex lentiformis, Atriplex torreyi, Baccharis salicifolia, Baccharis sergiloides, Salix exigua, Suaeda moquinii, and Tamarix spp. The alliance is found in the Great Central Valley and desert areas of California, Nevada, Utah and Arizona on playas, basin floors, channel beds, spring-fed slopes, springs, seeps, irrigation ditches, canyon bottoms, stream borders, and seasonally flooded washes.

Common (Translated Scientific) Name: Arrow-weed Wet Shrubland Alliance

Colloquial Name: Arrow-weed Wet Shrubland

Hierarchy Level:  Alliance

Type Concept: Pluchea sericea is dominant or codominant in an open to continuous shrub layer with Allenrolfea occidentalis, Atriplex canescens, Atriplex lentiformis, Atriplex torreyi, Baccharis salicifolia, Baccharis sergiloides, Salix exigua, Suaeda moquinii, and Tamarix spp. Emergent trees may be present at low cover, including Populus fremontii, Populus balsamifera ssp. trichocarpa, or Prosopis glandulosa. The herbaceous layer is sparse to continuous and often includes Phragmites australis and sometimes includes Distichlis spicata. The alliance is found in the Great Central Valley and desert areas of California, Nevada, Utah and Arizona. It occurs on playas, basin floors, channel beds, spring-fed slopes, springs, seeps, irrigation ditches, canyon bottoms, stream borders, and seasonally flooded washes. Soils are alluvial- or eolian-derived sands or clay loams from a variety of substrates that are usually alkaline or saline. Textures are variable.

Diagnostic Characteristics: Pluchea sericea =2% absolute cover; no other species with greater than or equal cover in the shrub canopy (Thomas et al. 2004).

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: No Data Available

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: The alliance forms an open to continuous shrub layer and the overall shrub cover ranges from 2.5 to 92%. The tree layer is typically sparse to open, and the herb layer is sparse to continuous. Nonvascular plants are typically sparse to open.

Floristics: Pluchea sericea is dominant and characteristic in the shrub layer, which is sometimes accompanied by Allenrolfea occidentalis. Other shrubs may include Atriplex canescens, Atriplex lentiformis, Atriplex torreyi, Baccharis salicifolia, Baccharis sergiloides, Salix exigua, Suaeda moquinii, and Tamarix spp. Emergent trees may be present at low cover, including Populus fremontii, Populus balsamifera ssp. trichocarpa (= Populus trichocarpa), or Prosopis glandulosa. The herbaceous layer often includes Phragmites australis and sometimes includes Distichlis spicata.

Dynamics:  Pluchea sericea stands form thickets along permanent springs and slow-flowing streams or occur in vegetation mosaics surrounding alkali springs and marshes. It can tolerate strongly alkaline/saline conditions, and invasion by Tamarix is a concern since it and Pluchea sericea have similar water requirements as phreatophytes.

Stands occur as dense, narrow thickets along permanent springs and slow-flowing streams or as part of vegetation mosaics that surround alkali springs and marshes involving the Distichlis spicata, Prosopis glandulosa, Salix exigua, Schoenoplectus americanus, and Sporobolus airoides alliances (Sawyer et al. 2009). Stands can also exist with a "cornstalk" or "cornfield"-like appearance on extensive flats and playas that have strongly alkaline crusts. Groundwater is typically available a few feet below the surface but is rarely present at the surface. The cornfield and spring types have different ecological regimes. The cornfield type appears to establish under abnormally wet conditions, and it persists by tapping into the subterranean water supplies. Once established, wind-induced deflation and accretion isolate the shrubs, and they build up fine sandy soil mounds around the shrub bases. The spring type experiences occasional flooding events and dieback from fluctuations in the water table.
Environmental Description:  The alliance occurs from low to mid elevations on playas, basin floors, channel beds, spring-fed slopes, springs, seeps, irrigation ditches, canyon bottoms, stream borders, and seasonally flooded washes that have subterranean water. Access to moisture is essential, in which groundwater is available year-round and typically within 1-3 m of the ground surface. Aspect is variable. Soils are alluvial and derived from a variety of substrates, and soil textures are variable.
Geographic Range: The alliance is found in the Great Central Valley and desert areas of California, Nevada, Utah and Arizona, and possibly extending into Mexico.

Nations: MX?,US

States/Provinces:  AZ, CA, NV, UT


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: G3

Greasons: No Data Available
Type Name Database Code Classification Code
Class 2 Shrub & Herb Vegetation Class C02 2
Subclass 2.C Shrub & Herb Wetland Subclass S44 2.C
Formation 2.C.5 Salt Marsh Formation F035 2.C.5
Division 2.C.5.Nd North American Western Interior Brackish Marsh, Playa & Shrubland Division D036 2.C.5.Nd
Macrogroup 2.C.5.Nd.1 Warm & Cool Desert Alkali-Saline Marsh, Playa & Shrubland Macrogroup M082 2.C.5.Nd.1
Group 2.C.5.Nd.1.b Greasewood - Saltbush species Alkaline-Saline Wet Scrub Group G537 2.C.5.Nd.1.b
Alliance A0798 Arrow-weed Wet Shrubland Alliance A0798 2.C.5.Nd.1.b
Association CEGL003080 Arrow-weed Wet Shrubland CEGL003080 2.C.5.Nd.1.b
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Pluchea sericea (Arrow weed thickets) Alliance (Sawyer et al. 2009) [63.710.00]
= Pluchea sericea Shrubland Alliance (CNPS 2017) [63.710.00]
= Pluchea sericea Shrubland Alliance (Evens et al. 2014)
= Arrow weed series (Sawyer and Keeler-Wolf 1995)
= Arrowweed Scrub (#63820) (Holland 1986b)
Concept Author(s): J.O. Sawyer et al. (2009)

Author of Description: M.J. Russo after Sawyer et al. (2009)

Acknowledgements: No Data Available

Version Date: 03-20-15
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