Plant Assessment Form

Watsonia meriana

Synonyms: Watsonia bulbullifera Mathews & L. Bolus; Watsonia meriana (L.) Miller var. bulbullifera Mathews & L. Bolus; Watsonia bulbifera; Watsonia angusta auct. non Ker-Gawl.

Common Names: bulbil watsonia; watsonia

Evaluated on: 8/20/04

List committee review date: 27/08/2004

Re-evaluation date:

Evaluator(s)

Peter J. Warner
California Department of Parks and Recreation; CNPS; Cal-IPC
P. O. Box 603, Little River, CA 95456
(707) 937-9172 (w); (707) 937-2278 (h)
pwarner@mcn.org

List commitee members

Peter Warner
Joe DiTomaso
Alison Stanton
Cynthia Roye
John Randall
Jake Sigg

General Comments

Very little substantive literature on ecology and biology of this taxon was available for this assessment. Most responses based on personal observations of the reviewer.

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited
Alert Status? No Alert
Documentation? 1.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U Reviewed Scientific Publication
Impact?
Four-part score UBCD Total Score
C
1.2 ?Impact on plant community B. Moderate Observational
1.3 ?Impact on higher trophic levels C. Minor Other Published Material
1.4 ?Impact on genetic integrity D. None Other Published Material
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate
Invasiveness?
Total Points
11 Total Score B
2.2 ?Local rate of spread with no management B. Increases less rapidly
2.3 ?Recent trend in total area infested within state B. Increasing less rapidly
2.4 ?Innate reproductive potential
(see Worksheet A)
C. Low Other Published Material
2.5 ?Potential for human-caused dispersal B. Moderate
2.6 ? Potential for natural long-distance dispersal D. None
2.7 ?Other regions invaded B. Invades 1 or 2 ecological types
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Observational
Distribution?
Total Score C
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Observational

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".

Section 1: Impact
Question 1.1 Impact on abiotic ecosystem processes? U Reviewed Scientific Publication
Identify ecosystem processes impacted:

No information located.


Sources of information:

Question 1.2 Impact on plant community composition,
structure, and interactions?
B Observational
Identify type of impact or alteration:

Forms a dense carpet of corms at or near the soil surface, inhibiting germination or growth of other species, and resulting in a very dense colony of Watsonia over time, feasibly resulting in loss of native herbaceous or shrub species in local areas. Does not appear to affect the growth of existing overstory plants negatively. Colonies tend to expand, in part, due to avoidance of Watsonia as forage (by deer, rabbits). Observations of dense patches.


Sources of information:

Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org


Question 1.3 Impact on higher trophic levels? C Other Published Material
Identify type of impact or alteration:

Unpalatable to sheep and cattle (1); not observed as forage for deer (2) Cited as unpalatable, and not observed used as forage for native herbivores, so growth of Watsonia colonies will displace native forage species, reducing choices for native herbivores in local areas. However, this assessment is conservative, given the lack of quantitative data.


Sources of information:

1. Government of South Australia, Animal and Plant Control Commission. Weed Control Notes: Bulbil Watsonia. 2 pp.
2. Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org


Question 1.4 Impact on genetic integrity? D Other Published Material

None known, but unlikely. No congeners are native in California (1). Cross-generic hybridization is very rare.


Sources of information:

1. Hickman, JC (editor). 1993. The Jepson Manual: Higher Plants of California (Third Printing, with corrections). University of California Press, Berkeley. p. 1156.


Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
B
Describe role of disturbance:

Human-caused and natural disturbance will aid in establishment, but new populations have been observed in relatively undisturbed sites. Watsonia's greatest success seems to be in areas that are frequently mowed. However, it prospers and spreads without this type of regular disturbance. observations


Sources of information:

Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org


Question 2.2 Local rate of spread with no management? B
Describe rate of spread:

Spreads rather slowly from pioneer plants, but rate increases once bulbils (vegetative propagules borne on the stems; also called "cormils") become abunda nt. Observed spreading slowly in several sites along Sonoma and Mendocino County coast.


Sources of information:

Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org


Question 2.3 Recent trend in total area infested within state? B
Describe trend:

Increasing slowly - new populations noted regularly along Sonoma and Mendocino coast. Lack of management + unexploited, suitable habitat = increase in area infested


Sources of information:

Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org


Question 2.4 Innate reproductive potential? C Other Published Material
Describe key reproductive characteristics:

Reproduces only vegetatively, by bulbils (cormils) produced on flowering stems. Lack of genetic diversity may be a positive factor in keeping this cultivated plant from invading new habitats.


Sources of information:

Castillo, Alberto. 2004. Personal communication @
lists.ibiblio.org/pipermail/pbs/2003-August/014794.html
Day, P. 2003. Watsonia Control _ a proven success. @ http://members.iinet.net.au/!ewan/watsonia_peter.htm
Government of South Australia, Animal and Plant Control Commission. Weed Control Notes: Bulbil Watsonia. 2 pp.
Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org


Question 2.5 Potential for human-caused dispersal? B
Identify dispersal mechanisms:

Bulbils can be easily dispersed through mowing or other movement of plant debris or soil (1,2); rhizomes may less frequently be moved in soil, or in discarded landscape maintenance debris (2). observations and deductive reasoning (2)


Sources of information:

1. Government of South Australia, Animal and Plant Control Commission. Weed Control Notes: Bulbil Watsonia. 2 pp.
2. Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org


Question 2.6 Potential for natural long-distance dispersal? D
Identify dispersal mechanisms:

Dispersal by natural means (animals, water, wind) of bulbils or rhizomes (the only available reproductive structures (1,2,3,4)) would appear to be extremely rare, barring an enormous flood flowing through an established population. physical evidence and deductive reasoning (5)


Sources of information:

1. Castillo, Alberto. 2004. Personal communication @
lists.ibiblio.org/pipermail/pbs/2003-August/014794.html
2. Day, P. 2003. Watsonia Control _ a proven success. @ http://members.iinet.net.au/!ewan/watsonia_peter.htm
3. Government of South Australia, Animal and Plant Control Commission. Weed Control Notes: Bulbil Watsonia. 2 pp.
4. Hickman, JC (editor). 1993. The Jepson Manual: Higher Plants of California (Third Printing, with corrections). University of California Press, Berkeley. p. 1156.
5. Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org


Question 2.7 Other regions invaded? B
Identify other regions:

Australia (1,2) - riparian, native vegetation (2); Uruguay and Argentina (3) Watsonia is not currently invasive in riparian areas along Sonoma and Mendocino coast, so this habitat may be vulnerable, in this area and elsewhere.


Sources of information:

1. Day, P. 2003. Watsonia Control _ a proven success. @ http://members.iinet.net.au/!ewan/watsonia_peter.htm
2. Government of South Australia, Animal and Plant Control Commission. Weed Control Notes: Bulbil Watsonia. 2 pp.
3. Castillo, Alberto. 2004. Personal communication @
lists.ibiblio.org/pipermail/pbs/2003-August/014794.html
4. Calflora Database. 2004. www.calflora.org


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? B Observational

Invades coastal prairie and closed cone pine stands in Sonoma and Mendocino Counties. However, these two habitat types are interspersed and differ very little in climate, although soil types may vary somewhat. 2 major ecological types invaded, but distribution is quite narrowly constrained.


Sources of information:

Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org
Calflora Database. 2004. www.calflora.org


Question 3.2 Distribution/Peak frequency? D Observational
Describe distribution:

Infrequently encountered in coastal prairie or closed-cone pine forests, even within known range (Sonoma and Mendocino coast). Based on numerous observations.


Sources of information:

Warner, PJ. 2000-2004. Personal observations in Sonoma and Mendocino Counties. 707/937-9172; pwarner@mcn.org


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less No
Dense infestations produce >1,000 viable seed per square meter No
Populations of this species produce seeds every year. No
Seed production sustained over 3 or more months within a population annually No
Seeds remain viable in soil for three or more years No
Viable seed produced with both self-pollination and cross-pollination Unknown
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes Yes
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned Yes
Total points: 2
Total unknowns: 1
Total score: C?

Related traits:

reproduces vegetatively only, by bulbils (cormils) produced on flowering stems, or by tranplanting of the rhizomes.

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)
Major Ecological Types Minor Ecological Types Code?
Marine Systemsmarine systems
Freshwater and Estuarine lakes, ponds, reservoirs
Aquatic Systemsrivers, streams, canals
estuaries
Dunescoastal
desert
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrub
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairieD, < 5%
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forestD, < 5%
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): B
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

  • Central West
  • Northwest