| BEN |
| BOTANICAL ELECTRONIC NEWS |
|---|
| ISSN 1188-603X |
| No. 292 June 28, 2002 | aceska@victoria.tc.ca | Victoria, B.C. |
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The following key will facilitate identification of most specimens of Platanthera encountered in the Pacific Northwest. However, some hybridization does occur, and it may be an important factor in some areas. Although in many cases hybrids are intermediate between their parents, or display a mixture of parental features, in some cases they do not. Instead, these plants revert to a basic, presumably ancestral form, with green lanceolate lip and clavate spur about equaling the lip in length. Such plants are generated by hybridization of different species across a wide geographic area. When struggling to identify a plant with such characteristics, it is well to keep this situation in mind. Contributing even further to the problem is a complex of similar forms at the southern edge of the region that may intergrade with Platanthera sparsiflora. This group, which is currently under study, is not yet taxonomically resolved.
The key employs characters of the column which may not be familiar to many who do not routinely work with orchids. When a Platanthera flower is viewed in its normal position, the lip is lowermost (in the species considered here). The column is in the center of the flower, with the anther above the stigma. The anther is composed of two anther sacs separated by the connective. Each anther sac encloses one pollinarium. Each pollinarium is composed of one pollen mass, the pollinium, at the top, connected by a stalk to a sticky membranaceous disc, the viscidium, which glues the pollinium to the pollinator. The viscidia are presented at the lower ends of the anther sacs, which are born on rostellum lobes that position the viscidia for contact with visiting pollinators. In a general way they flank the opening to the spur. The shapes and orientations of these various structures reflect specializations for different pollination syndromes that give rise to mechanical and behavioral isolating mechanisms. Hence they are important characteristics that serve to delimit species.
1. Leaves 1 -- 2, the scape naked or with 1 to few markedly
reduced bracts ....... 2
2. Spur saccate, lip broadly elliptic-suborbicular to
obovate, concave......................... P. chorisiana
2. Spur slender, lip linear to rhombic-lanceolate, more or
less flat ......... 3
3. Leaf 1, or if 2, alternate and widely spaced on the
stem, erect- spreading ................. P. obtusata
3. Leaves 2 in a basal pair, wide-spreading and commonly
lying on the ground .................. P. orbiculata
1. Leaves 3 -- several, gradually reduced to bracts upwards .. 4
4. Column comparatively large, occupying about 2/3 of the
hood formed by the dorsal sepal and petals, the rostellum
lobes widely spaced, diverging, elevated above the surface
of the stigma and connective and with them forming a
hemispherical chamber; lip linear to linear-oblong or
linear-lanceolate or narrowly elliptic, the base undilated
........................................ P. sparsiflora
4. Column comparatively small, occupying less than half of
the hood formed by the dorsal sepal and petals, the ros-
tellum lobes parallel, diverging, or converging but
scarcely elevated, at most separated by a narrow slit and
not forming a hemispherical chamber; lip linear to linear-
lanceolate, rhombic-linear, rhombic-lanceolate, or ellip-
tic, the base undilated or with an obscure to orbicular
basal dilation ...... 5
5. Anther low and appearing to lie atop the stigma, the
anther sacs widely diverging from apices scarcely
separated by an obscure connective; flowers autogamous,
the pollinia rotated forward, commonly free of the
anther sacs and/or fragmenting into loose masses that
trail downward onto the stigma; spur clavate, mostly
slightly shorter than the lip; lip rhombic-lanceolate,
yellowish to yellowish green .......... P. aquilonis
5. Anther high and rising above the stigma, the anther
sacs more nearly parallel, converging, or diverging
from apices separated by an evident connective; flowers
not autogamous (except sometimes so in P.
huronensis), the pollinia remaining within the anther
sacs; spur saccate to slenderly clavate or filiform,
much shorter to much longer than the lip; lip linear to
elliptic or broadly lanceolate or with an abrupt basal
dilation, white to green or yellowish ..... 6
6. Pollinaria and rostellum lobes parallel to converg-
ing toward the orbicular viscidia; spur saccate to
spatuloid-capitate or strongly clavate, much shorter
than lip ............................. P. stricta
6. Pollinaria and rostellum lobes diverging toward the
oblong or sometimes (in P. purpurascens) orbicular
viscidia; spur slenderly cylindrical to strongly
clavate or saccate, slightly longer to much shorter
than the lip ....... 7
7. Flowers pure white, lip usually with a pronounced
rounded basal dilation, or rarely shallowly 3-
lobed ( the broad dilation elaborated into
forward-directed lobules); spur slender to
clavate or slightly capitate [P. dilatata] .. 8
8. Spur much longer than the lip, usually very
slender; typically fragrant only at night
........... P. dilatata var. leucostachys
8. Spur shorter than the lip or of variable
length, typically rather stout to clavate;
fragrant during the day [plants with slender
spurs about the length of the lip may in some
cases represent var. dilatata]
.............. P. dilatata var. albiflora
7. Flowers greenish in general aspect, lip greenish
or yellowish, mostly lanceolate to ovate or
linear, sometimes obscurely or prominently di-
lated at the base; spur slenderly cylindrical to
strongly clavate or saccate, shorter than to
slightly longer than the lip .... 9
9. Spur saccate to clavate-inflated, about half
the length of the lip; Lip yellowish green to
dull yellowish or intensely bluish green,
sometimes marked with red; viscidia usually
orbicular; musty-scented (central Sierra
Nevada, California, where disjunct from
southern Rocky Mountains)
........................... P. purpurascens
9. Spur slenderly clavate to slenderly cylindri-
cal, not inflated and merely obtuse to sub-
acute, somewhat shorter to slighter longer
than the lip; lip whitish green; viscidia
oblong; sweet scented; widespread
............................. P. huronensis
Selected References
During a survey of rare plants on a property that is being developed into a golf course, we encountered Ranunculus parviflorus L., a species not yet reported from British Columbia. It was growing in wet places on the proposed fairways, and it most probably came with the grass seed used for seeding exposed soil. Ranunculus parviflorus is native to Europe (Mediterranean region and western Europe), and in North America it is adventive to the SE part of the USA. In western North America it has been collected in northwestern California (as early as 1922), Oregon (first collected in 1981 - see Madrono 33: 312,313. 1986) and Washington (first collected probably in 1995 - D. Giblin, WTU, personal communication). It was expected to eventually appear in SW British Columbia.
Ranunculus parviflorus is an annual buttercup that occurs in vernally wet depressions. It is a low plant, 5 to 40 cm tall, spreading to decumbent. The lower leaves are 3- to 5-lobed, the upper one are simple. Stem and leaves are pubescent. Flowers are small, 3-6 mm in diameter. Achenes are 2-3 mm with hooked spines and short hooked beak. Receptacle is glabrous. The plant reminded us of a miniature Ranunculus uncinatus. Its potential to become a serious problem in this area is negligible, although in New Zealand it was reported as an unwanted weed in meadowfoam fields (Limnanthes alba).
Voucher specimen: Victoria, Saanich Municipality. Seeding at the fairways of the proposed golf course at the northern end of Creed Road, 48 deg. 28' 16.5" N. 123 deg. 26' 58.0" W. March 10, 2002, A. & O. Ceska, # 32,645
If you think there is a possibility you might visit Montana be SURE to acquire Peter Lesica's new Flora of Glacier National Park. Better yet, purchase the book now and plan a trip to Montana as soon as possible! This is a wonderful new work -- the first new flora of Glacier Park in more than 80 years. Peter has included everything one could possibly want in a regional flora: a full Introduction which discusses climate, geology, vegetation patterns, history of botanical exploration, floristics, notes on plant geography, and a topographic map of the park The book contains a solid 519 pages with a splendid cover photograph by Lesica of one of our most spectacular mountain species, Xerophyllum tenax, bear grass. The work is the result of twenty years of research on the part of the author who has hiked every trail in the park with, in his words, "a good deal of bushwhacking as well." The floristic summary indicates that 1,182 taxa -- Pteridophytes, Confers, Dicots and Moncots -- are keyed and described. Over one-third of these are illustrated with very effective line drawings by artist Debbie McNeil.
Other strengths are: alphabetical arrangement of families, genera and species, color photos arranged by habitat, nine pages of up-to-date references including our Oregon Flora Project Asteraceae Checklist, an excellent system of coordinating drawings and color photos with plant descriptions, use of synonyms where needed, a nine-page glossary, full treatments of willows, grasses, sedges, rushes and other difficult groups, centimeter ruler on the back cover.
I am so enthusiastic about the new book that I am almost embarrassed to offer a couple of minor suggestions for improvement, but here goes: I would like to see more emphasis on weedy species. For example the floral summary notes 127 introduced species in the Park and it would be helpful to have these listed and also set off in the descriptions with use of a different font as in the Jepson Manual. I would also like to see synonyms treated in a different font in the Index as in the Hitchcock manual. Of the 80 species of Carex described, only 7 are illustrated -- more drawings here would be most helpful, even if they showed only key characteristics. Despite the alphabetical treatments, it would be nice to have a family index inside the front cover. And the map should show the most familiar highway in the Park, the Going-to-the-Sun Road. Finally one last bit of nit-picking: that fantastic Montana state flower discovered by Lewis and Clark, Lewisia rediviva, bitterroot, is, alas, not illustrated in a drawing or colored photograph. Other than these minor items, I find this new work on Glacier Park a extremely welcome addition to our knowledge of the western flora. Congratulations, Peter and OSU Press!