White meconella (Meconella oregana) COSEWIC assessment and status report: chapter 6

Biology

Life cycle and reproduction

Meconella oregana blooms in March to early April throughout its range and the blooming period is highly weather dependent (Rush et al. 1999; California Native Plant Society 2003; NatureServe 2003; Washington Natural Heritage Program 2004, writer’s observations 2004). Known populations can be very difficult to find in some years and very abundant in other years (Janszen pers. comm. 2004) in part because this annual species is very difficult to locate when not in bloom.

Table 1. Occurrence records, confirmed records, and land status
Location on record Collector(s) and Year Herbarium Records Notes Field- checked in 2004 (or why not checked) Population  in 2004 Land and Protection Status Size of population (or subpo- pulation)
Mt. Douglas (=Cedar Hill) Macoun, 1875, 1876, 1884, 1887;
C.F. Newcombe, 1916;
Redfern, 1925;
Hardy, 1945, 1952
CMN (1975, 1976, 1887) all on same herbarium sheet; RBCM (1916, 1925, 1945, 1952) 1916: “small colony”
x
not found Regional Park
“Victoria” 1 Dawson, 1876;
Macoun, 1908
CMN (1876, 1908)   (exact location unknown)1 not found mostly private
DepartureBay, Jesse Island Spread borough, 1910 CMN (1910)   (privately owned island) not examined private
“Tod Inlet, Victoria” Hardy, 1927 RBCM (1927)   (exact location unknown) not found various
Little Saanich Mtn., Saanich C.F. Newcombe, 1917, 1928, 1931;
Hardy, 1931; Ceska, 1977, 1980;
Roemer, 2001, 2003
RBCM (1917, 1928, 1931a, 1931b, 1977) 1917: “single plant” 2003: “ one of two subpopulations, approx. 20 individuals on 2 sqm”
x
extant Federal portion
150
Private portion
302
“Elk Lake” Henson, 1933 UBC (1933)   (exact location unknown) not found various
Mt. Finlayson, Victoria Carter, 1918; Hardy, 1925, 1936 RBCM (1918, 1925); UBC (1936)  
x
not found Provincial Park
Thetis Lake Park, Victoria Clark, 1958; Melburn, 1958, 1961 UVIC (1958a);
RBCM (1958b)
 
x
extant Regional Park
368
Saturna Island Janszen, 1974, 1987 RBCM (1974) 1987?: “lots of plants; only found in one small area”
x
extant private
52
Nanoose Hill Ceska, 1976, 1993;
Douglas, 1976; Schofield, 1976
RBCM (1976a, 1976b); UBC (1976) 1976: “ two small populations (~10 plants?)”
x
not found Federal property
Jocelyn Hill, Highlands District Ceska, 1977, 1986;
Roemer, 1997
RBCM (1977, 1997)  
x
not found Provincial Park
Galiano Island, Sutil Mtn. Janszen, 1980 RBCM (1980)  
x
not found Galiano Conservancy and private
Mt. Tzuhalem Ecological Reserve William Newcombe, 1928;
Ceska, 1980
(Observations?)  
x
not found Provincial Ecological Reserve
NE of Port Alberni VanDieren, 1993a;
Ceska, 1993b
RBCM (1993a) 1993b: “several thousand plants”
x
extant private
1274
Skirt Mountain South Ceska & Roemer, 2000, 2003   2003: “300+30 reproductive individuals”
x
extant private
1209
Total: 15 Locations      
11/15
5 extant popns.   confirmed number 3355

2806 unprotected on private land; 151 unprotected on federal land; 368 protected in Regional Park

1 For place names in “quotes”, the exact locations are unknown because the locality descriptions are too inclusive and may overlap with other, more accurately pinpointed locations. In the intervening 70 or more years since these records were made the locations also have been subject to urban or at least residential development.

Table 2. Search effort for Meconella oregana in 2004
  Localities (all surveys by writer, except where otherwise indicated in date column) Survey dates mm/dd (all 2004) Number of Meconella plants (highest total if visited repeatedly)
Known localities where species was found in the past Mt. Douglas, Saanich Municipality 03/28, 04/07
Known localities where species was found in the past Little Saanich Mtn., Saanich Municipality 03/11, 03/13, 03/19, 03/26, 03/29, 04/06, 04/09
422
Known localities where species was found in the past Mt. Finlayson, Langford Municipality 04/18
Known localities where species was found in the past Thetis Lake Park, View Royal Municipality 03/23, 03/30, 04/01
368
Known localities where species was found in the past Saturna Island 03/22 04/05 (H.Janszen)
52
Known localities where species was found in the past Nanoose Hill 03/16
Known localities where species was found in the past Jocelyn Hill, Highlands District 03/27, 04/19
Known localities where species was found in the past Sutil Mtn., Galiano Island 03/24
Known localities where species was found in the past Mt. Tzuhalem Ecological Reserve, Duncan 04/02 (A. & O.Ceska)
Known localities where species was found in the past NE of Port Alberni 04/02
1274
Known localities where species was found in the past Skirt Mountain South, Langford Municipality 03/12, 03/13
1209
Unknown or lost localities where species was found in the past; too poorly defined “Victoria”: Exact locality unknown; overlaps with several of the surveyed localities  
Unknown or lost localities where species was found in the past; too poorly defined “Tod Inlet”: “Victoria”: Exact locality unknown; promising natural habitats are developed  
Unknown or lost localities where species was found in the past; too poorly defined “Elk Lake”: Exact locality unknown; overlaps with two of the surveyed localities  
Known locality, not visited Departure Bay, Jesse Island: (privately owned island)  
Additional localities with promising habitats Bear Hill, Saanich Municipality 03/(18?)
Additional localities with promising habitats Skirt Mountain West, Langford Municipality 03/17, 03/21
Additional localities with promising habitats Mill Hill, Langford Municipality 03/20, 04/12, + many later visits
Additional localities with promising habitats Mathews Point, Galiano Island 03/24
Additional localities with promising habitats Stewart Mtn., Highlands District 03/23
Additional localities with promising habitats Lone Tree Hill, Highlands District 03/27
Total    
3355

Very little information is known about the reproductive biology of Meconella oregana. Platystemon californicus, a closely related annual species from California is highly self-incompatible and has a high pollen:ovule ratio (Hannan, 1981). Although solitary bees pollinate P. californicus(Andrenidae and Halictidae), the plants are also wind pollinated (Hannan, 1981). Although Meconella oregana has a low number of stamens and fairly small stigmas, the high density of the plants may allow effective wind pollination (Hannan, pers. comm. 2004) especially since few pollinators are active in the early spring when it blooms. Although Meconella oregana is probably partially self-compatible, the stigmas expand above the anthers a day or two after anthesis to increase the potential for outcrossing (Ernst 1967). The petals close at night, which excludes the possibility of night pollinators (Ernst 1967).

In greenhouse experiments at Stanford University, Ernst (1967) found Meconella species difficult to grow: seedlings were susceptible to damping off and often required more than one year to germinate. Adding gravel to the top of pots helped aerate the base of the plants and prevented seeds from washing away (Ernst 1967). In Victoria Meconella oregana has in two instances been observed to germinate in the fall (Pinder-Moss, pers. comm. 2004, Hans Roemer's observations 2004/2005); however, at Stanford, it was observed to germinate in the spring. In natural habitats germination was found to begin after a wet/warm spell in late January (Hans Roemer's observation 2005).

Meconella oregana is an annual and the plant dies after producing seed. The seed may have a limited life expectancy because old seed does not germinate readily (Pinder-Moss, pers. comm. 2004).

Herbivory

Herbivores affecting Meconella oregana are not listed in any published literature and no signs of herbivory were observed in the field in 2004. The specific function of protopine and the additional alkaloid found in the closely related Meconella californica is not known. However, in other species, alkaloids are known to deter pathogens including bacteria, fungi, insects, nematodes and protozoa (Salmore and Hunter 2001). Alkaloids may also deter other herbivores.

Physiology

There is no literature on the physiological requirements and tolerances of Meconella oregana. The closely related Meconella californicahas been found to contain the alkaloid protopine in addition to a second minor alkaloid that could not be re-extracted in sufficient quantity for identification (Stermitz and Coomes 1969). In conditions of water stress, the closely related species, Platystemon californicus, was found to have decreased water potential, lower stomatal conductance and decreased photosynthesis. Platystemon californicusis not particularly sensitive to increased ozone levels (Bytnerowicz et al. 1988).

Dispersal

Meconella oregana produces many-seeded capsules that dehisce apically by three valvelike carpels. The carpels separate at maturity and occasionally twist (Gunn and Seldin 1976; Gunn 1980) releasing the seed. Although seed of other genera in the Papaveraceae have arils that attract ants as seed dispersers, Meconella oregana seed does not have arils (Ernst 1962; Gunn and Seldin 1976; Gunn 1980). Because of the small size of this plant, the small seeds (compare morphological description) and the lack of arils, dispersal distance from the parent plant is probably very limited. This is borne out by the very small areas occupied by the Canadian subpopulations. The average patch size of all 17 subpopulations found in 2004 was 3.4 . However, it ranged as low as 0.03 m² (Figure 4). The fact that several subpopulations were found straddling deer trails suggests that longer-distance dispersal may occur with clumps of moist soil on the hooves of these animals (Hans Roemer's observations 2004).

Figure 4. Fifty Meconella plants at the Port Albernisite marked for counting. Note shallow soil and bike tracks.

Figure 4. Fifty Meconella plants at the Port Albernisite marked for counting. Note shallow soil and bike tracks.

Interspecific interactions

Fire may have played a role in maintaining habitat for Meconella oregana. Regular fires would have decreased competition by reducing shrub invasion and decreasing the growth of grasses and forbs (Rush et al. 1999; Washington Natural Heritage Program 2004). Populations of Meconella oregana are probably negatively impacted by competition from exotic annual grasses (Ertter pers. comm. 2004; Washington Natural Heritage Program 2004), which are very effective at capturing spring moisture. In the Canadian habitats, 25 non-native plants were among the associates of Meconella, seven of them exotic annual and biennial grass species.

Adaptability

As would be expected for an annual, the size of Meconella oregana plants and flowers changes in response to variations in seasonal rainfall and temperature (Ernst 1967). In 2004 the writer observed flowering specimens between 1 and 8 cm tall which ranged from single-stemmed to branched with up to five stems. Open flowers ranged from 2 to 6 mm in diameter. The largest plants occurred in less exposed and more sheltered, or in partly shaded microhabitats. Meconella plants were also observed to have their flowering period shorter and earlier in dry habitats and longer and later in seepage areas.

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