| BEN |
| BOTANICAL ELECTRONIC NEWS |
|---|
| ISSN 1188-603X |
| No. 428 October 21, 2010 | aceska@telus.net | Victoria, B.C. |
|---|
In early August of 2010, I discovered an individual plant of Abronia umbellata subsp. breviflora (Standl.) Munz (Pink Sand-verbena) growing on a beach in Florencia Bay, between Tofino and Ucluelet on the west coast of Vancouver Island. The plant was vigorous, had about 70 cm of stem material, and bore a single flower cluster. It occurred a few metres below the driftwood zone, on an area of beach which is above the reach of summer tides but is overrun by winter storm surges. Soon afterwards, Barry Campbell found a second plant of similar size farther down the same beach. Later in August, Barry and I independently discovered a single individual on the beach at Schooner Bay, nearer Tofino.
Abronia umbellata subsp. breviflora occurs south along the beaches and dunes of British Columbia, Washington, Oregon and California as far as the Point Reyes area, near San Francisco. It is ranked globally imperilled (NatureServe 2009). Southwards from San Francisco it is replaced by A. umbellata Lam. subsp. umbellata. Tillett (1967) assigned populations in Canada and Washington to A. umbellata subsp. acutalata (Standl.) Tillett, however, examinations of morphology and chloroplast DNA failed to show any difference between subsp. acutalata and subsp. breviflora (Karoly ex Kaye 2002) so northern plants are now assigned to subsp. breviflora In Canada. Abronia umbellata subsp. breviflora is ranked as endangered and protected under the Species-at-Risk Act (Douglas 2000, 2004; Fairbarns 2010).
There are several older Canadian records of Abronia umbellata subsp. breviflora, all from beaches along the west coast of southern Vancouver Island. C.F. Newcombe collected it from a sand beach in the Ahousat area (either on Flores or Vargas Island) in 1915. It was collected at Pachena Bay in 1909 (G. Fraser), in 1918 (J.R. Anderson) and in 1927 (A. Evans). It was also collected at Bamfield Creek in 1917 (A.R. Sherwood). There are no subsequent reports of the species at any of these three locations. It has also been collected in the northern Olympic Peninsula at least three times (C. Piper 1895, E. Webster 1910 and M. Ownbey 1940).
In 2000, Jim Hamilton reported two robust plants growing on the beach along Clo-oose Bay. They were growing within a few metres of where the species had been seen in the early 1940's, as confirmed by Dulcie Cox who lived there at the time. The Clo-oose Bay plants died in the winter of 2000/2001 but Hamilton had collected seeds from the population and used some of them to grow a cluster of plants on the beaches of Clo-oose Bay in the subsequent year. None of those plants survived the following winter. In 2008, Parks Canada began a series of experimental re-introductions in Pacific Rim National Park Reserve, using second generation plants derived from the balance of the seeds collected by Hamilton (Fairbarns 2010).
Greenhouse studies have shown that Abronia umbellata may persist as a perennial under favourable conditions but field monitoring has shown that it is unable to survive winters along the southwest coast of Vancouver Island, even where it is protected from winter tides (Fairbarns 2010). Three explanations have been proposed for its repeated occurrence in Canada: deliberate planting, persistence in a buried seedbank and repeated natural introductions from southern populations.
The species was deliberately planted at Clo-oose Bay as an unauthorized experiment in 2001. It was planted there again from 2008 and 2009 as part of a formal re-introduction project (Fairbarns 2010). It seems unlikely, however, that individuals collected/observed near Ahousat in 1915, at "Bamfield Creek" in 1917, at Pachena Bay in 1909, 1918 and 1927, at Clo-oose Bay in the early 1940's, or at Florencia Bay and Schooner Cove in 2010 were planted.
The observation of plants at Clo-oose Bay in 2000, very close to where they grew in the early 1940's, strongly suggests that the species is also capable of "dispersing in time" - that is, persisting in a soil seed bank until circumstances allow it to successfully regenerate in place. There is independent evidence that the seeds may remain viable for long periods.
Apart from the three collections made at Pachena Bay between 1909 and 1927, Kaye (2004) also reports the re-discovery of Abronia umbellata subsp. breviflora at Tenmile Creek in southern Oregon, adjacent to a historic site. Kaye (2001) demonstrated that the loss of viability among seeds of Abronia umbellata subsp. breviflora appears to be very slow, at least in seeds stored in paper bags at room temperature. Over 90% of the seeds from one lot remained viable after 10 years storage. Similarly, several seeds collected from the Clo-oose Bay population in 2000 - first stored in a plastic bag and then in a glass jar - were successfully propagated in 2010. This year I also observed plants growing in a plot at Clo-oose where I had shallowly buried numerous fruit in 2008.
It seems probable that the plant is capable of dispersing across great distances in long-shore currents. The Canadian populations, along the periphery of the taxon's range are presumably derived from a more southern source and the plant's strict coastline distribution leaves little doubt that dispersal occurred in the ocean rather than on land. Perhaps there have been repeated natural introductions from populations in the U.S., but it also possible that there has been a single successful event of long-distance dispersal leading to the establishment of a northern stronghold, which has spread seed to the other Canadian locations where it has been observed. The plants observed at Florencia Bay and Schooner Cove may well have derived from seed produced in the experimental area at Clo-oose in 2008 and 2009. If this is true, they have made a remarkable 85 kilometre journey in, at most, two years (including a 20 km drift across the open waters of Barkley Sound).
Plants found on beach sites over-run by winter storms, may have a precarious toehold. Such sites may provide a stepping stone to sand dunes above the reach of winter tides. The natural population at Port Orford and the introduced population on the Coos Bay North Spit, both well above the reach of storm tides, are large and vigorous (pers. obs.). Natural occurrences have not yet been reported from sand dunes in Canada, however, and transplants on the Clo-oose dune had very low vigour (Fairbarns 2010).
Zvolanek, Zdenek. 2006. The Crevice Garden & its Plants. [Edited by Joyce Carruthers and John Good] Foreword by John Good Oct 2006 Alpine Garden Society [AGS Publications Limited], 68 p. Price £6.95
Ordering information: http://www.alpinegardensociety.net/sales/books/agspublications/Crevice+Gardening/123/
Zdenek Zvolanek is an excellent craftsman in rockwork and a knowledgeable & well-travelled plants-man. He cares deeply about plants. Crevice gardens provide a wide range of microhabitats in a very small space and hence enable the cultivation of plants with widely differing habitats.
Crevice gardens are not a new way of growing alpine plants, but there is a renewed interest in them as more and more people find that, if well constructed, they combine an attractive appearance with the ability to provide ideal homes for a wide range of alpines, including many of the choicer species. Zdenek Zvolanek ["Zee-Zee" in the rock gardening circles] is a major practitioner of the art of crevice gardening and has built successful examples on all scales from small troughs to the grand scale of an acre or more. Here he describes the concepts involved in crevice gardening, crevice garden construction, planting and maintenance, emphasizing the ability of crevice gardens to provide a wide range of micro-habitats in a small space, and hence enable the cultivation of plants with widely differing requirements.
In this small well-illustrated book Zdenek shows you how to craft a crevice garden from any stone including unprepossessing field boulders. With four figures and 22 colour plates, he demonstrates how to design and construct this unique garden bed. He lives in and references Victoria, B.C. and the Czech Republic and how he plants his gardens with the local climate in mind.
The second half of the book is a descriptive list of alpine plants suitable for this type of bed. His list reflects his preference for plants that once established, require no watering. The plants are also illustrated with 44 postage-size stamp colour photos to entice you to try them.
For the accompanying figures see:
http://bomi.ou.edu/ben/428/myriophyllum_ben428.pdf
Myriophyllum farwellii Morong - Farwell's Water-Milfoil
North American species distributed in eastern North America; in the Pacific
Northwest known from Alaska & British Columbia. Easily overlooked since it
grows relatively deep at the bottom of dystrophic lakes. Usually
copiously fruiting at the base of the stem leaves. Winter buds absent.
Myriophyllum heterophyllum Michx. - Two-Leaf Water-Milfoil
Introduced to Alberta, British Columbia and Washington from eastern North
America. In BC it occurs in a park ponds in Vancouver. Easily recognizable
by whitish stems and leaves in pseudowhorls. Winter buds absent.
Myriophyllum hippuroides Nutt. ex Torr. & Gray - Western Water-Milfoil
Occurs from California to the Lower Fraser Valley in British Columbia; there
it forms dense stands in sloughs of the Fraser River and its tributaries.
Easily recognized by deep green colour, dense foliage with additional
numerous leaves outside the whorls. Winter buds absent.
Myriophyllum pinnatum (Walt.) B.S.P. - Cut-Leaf Water-Milfoil
Eastern North American species with disjunct occurrences in British
Columbia, Washington and Oregon. Recognized by the dark-green stems and
foliage. Winter buds not seen.
Myriophyllum quitense Kunth - Andean Water-Milfoil
Syn.: M. elatinoides Gaud.
South American species that extends to western USA and to British Columbia;
also in eastern Canada. It occurs in wind-swept parts of large lakes or in
flowing water of rivers. Dried herbarium specimens are dark grey. The
lowermost leaves are reduced to bract-like structures and the system of
strong whitish roots are the best identification characters of the sterile
plants. Winter buds absent.
Myriophyllum sibiricum Komarov - Siberian Water-Milfoil
Syn.: M. exalbescens Fern.; M. spicatum subsp. exalbescens (Fern.)
Hultén
Native to North America, northern Europe and eastern Asia, widespread in
North America (except Texas and SE states). Stem whitish, leaves with
smaller number of "untidy" segments. Winter buds frequent, cylindrical.
Myriophyllum spicatum L. - Eurasian Water-Milfoil
Introduced and invasive. North American invasive populations are considered
tobe of a hybrid origin [M. spicatum x M. sibiricum] by Moody & Les
(2002, 2007). Stem drying reddish. No winter buds.
Myriophyllum ussuriense (Regel) Maxim. - Ussurian Water-Milfoil
Syn.: M. isoetophyllum Komarov
Amphiberingian species, Far East of Asia and British Columbia, Washington
and Oregon. Dioecious, population clonal, usually of one sex (female
populations prevailing) some populations rarely with hermaphroditic
individuals. Terrestrial or semiterrestrial at the margins of lakes and
rivers with fluctuating water table, truly aquatic plants rare. Habit is
unlike of any other our milfoil. Winter buds inconspicuous, filiform.
Myriophyllum verticillatum L. Whorled Water-Milfoil
Circumpolar species. Occurs sporadically throughout Canada, Pacific
Northwest, and NE parts of the USA. Stems and leaves green, leaves often
with "myriophylloid glands" at the base of the lowermost segments. Winter
buds frequent, clavate.
1. Leaves alternate or in whorls with additional alternate leaves scattered
outside the whorls.
2. Flowers in axils of submerged leaves, not forming terminal
spikes; alternate leaves more common than those in whorls
.................................. M. farwellii
2. Flowers in terminal spikes in axils of bracts; leaves essentially
in whorls with some alternate leaves scattered on the stem.
3. Fruits (mericarps) with tiny warts on the dorsal ridges
............................._M. pinnatum
3. Fruits (mericarps) with glabrous, rounded dorsal ridges.
4. Stems whitish, lighter than the leaves; leaves
dark green; bracts shallowly sharp-toothed;
bracteoles at the base of flowers
1-1.3 mm long; petals 1.5-3 mm long;
mericarps prominently beaked from
a persistent stigma
...................... M.heterophyllum
4. Bracts comb-like; bracteoles at the base of
flowers 0.6-0.7 mm long; petals 1-2 mm long;
mericarps without permanent beaks
......................._M. hippuroides
1. Leaves in regular whorls or opposite, but without any additional
alternate leaves scattered outside the whorls.
5. Plants dioecious usually forming single populations of the same
sex.
6. Plants robust; stems 2-5 mm in diameter; leaves usually
in whorls of 5 to 8
............................ M. aquaticum
6. Plants delicate; stems 1-2 mm in diameter; leaves in
whorls of 3 or 4, often also opposite
............................ M. ussuriense
5. Plants monoecious, male and female flowers in the same
inflorescence.
7. Floral bracts pinnate ... ..... M. verticillatum
7. Floral bracts entire or dentate.
8. Young shoots with one or several parts of entire
leaves at the base; plants with strong
whitish rhizomes; flower bracts
triangular, over 4 mm long, toothed;
bracteoles 1.0-1.5 mm long
......................._M. quitense
8. Young shoots lacking entire leaves at the base;
plants usually without whitish rhizomes;
flower bract lanceolate, less than 4 mm
long, entire or shallowly notched, lacking
a waxy bloom; bracteoles less than 1.0 mm
long.
9. Leaves with 14-24 pairs of segments;
segments declined in sharper than 45°
angle; segments parallel to each other
throughout the whole leaf
.................... M. spicatum
9. Leaves with 4-14 pairs of segments;
segments declined from 45° angle to
almost perpendicular to the axis
of the leaf, angles varying throughout
the leaf ............ M. sibiricum
Myriophyllum aquaticum (Vell.) Verdc. - Parrot's-Feather
Syn.: M. brasiliense Camb., M. proserpinacoides Gillies ex Hook. & Arn.
Introduced in North America from South America. Dioecious, only female
plants known in North America. Easily recognized by thick stems, firm leaves
and overall bright green colour. Winter buds absent.
Selected References
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