Lakeside daisy (Hymenoxys herbacea) COSEWIC assessment and update update status report: chapter 11

Technical Summary

Hymenoxys herbacea

Lakeside Daisy – Hyménoxys herbacé

Extent and Area Information

Extent of occurrence:

75,246 km²

Area of occupancy:

about 14 km²

Population information

Total number of individuals in the Canadian population:

471 million rosettes (ramets)

Number of mature reproducing individuals in the Canadian population:

> 6.8 million flowering rosettes

Generation time:

16 years (mean age at which new plants produce offspring)

Total population trend:

unknown, but some populations known to be declining

Rate of decline for total population:

  • ____% in 10 years or three generations,
  • _____ % decline in ____  years.

Number of known populations:

39 in Canada

Is the total population fragmented?

Yes

number of individuals in smallest population:

50 rosettes

number of individuals in largest population:

202,013,200 rosettes

number of extant sites:

38

number of historic sites from which species has been extirpated:

1

Does the species undergo fluctuations in numbers?

not significantly

If yes, what is the

  • maximum number? ______
  • minimum number? ______

Are these fluctuations greater than one order of magnitude?

No

Threats

Habitat destruction (quarry activity, cottage construction, human traffic and trampling), habitat availability.

Rescue Effect

Does the species exist outside of Canada? 

Yes

Is immigration known or possible?

No? ~ 0.6 migrants/generation among Canadian populations. Migration rate between Canadian and U.S. populations unknown, but highly unlikely. The two isolated U.S. populations are separated by large water bodies from suitable habitat in Canada.  This species does not disperse well and propagules would be unlikely to reach suitable habitat from U.S. populations

Would individuals from the nearest foreign population be adapted to survive in Canada?

Probably

Would sufficient suitable habitat be available for immigrants?

Yes, at least on Manitoulin Island and the Bruce Peninsula

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