Lomatium Identification
Mostly for species found in western and central Washington State. There are several other species in southeastern Washington that I have not yet observed and are not listed. Be sure to follow links for species - good pictures and often more detailed description. I also have a partial and very simplified key. This guide is somewhat idiosyncratic and mostly focuses on specific characters that I find useful in the field rather than a comprehensive description or key.
Useful non-technical slide show: Slides (this source says that seed dispersal is by water and rodent cache, but I would add wind dispersal, at least for species with fruit wings in the windier parts of central Washington (said winds have nearly dispersed me at times). The winged fruits sure look they are designed to be dispersed by high winds and not otherwise (winged fruits). By molecular studies, Lomatium and Cymopteris (and a few Tauschia and others) are extensively interdigitated, which appears not to have fully penetrated to formal naming. George et al 2014 Phylogenetic Analysis Reveals Multiple Cases of Morphological Parallelism and Taxonomic Polyphyly in Lomatium .
Some identification guides suggest crushing some leaves, but all of the species I have tested seem to smell roughly the same of cedar and turpentine, so smell can be useful to identify as Lomatium but not among species (on the other hand I do not have a discriminating nose).
Photo tips
A few Lomatiums can be identified by a single photo but most cannot.
Take several photos, possibly including:
1) the overall plant (not just the flower) and perhaps a text comment on size
2) the leaf structure (holding your hand or a sheet of something behind the leaf helps)
3) the underside of the secondary umbel (the base of the little cluster of flowers)
4) as close as you can get to a leaflet and the flower stem (some species have short hairs). Newer phones often have macro capability that is quite good.
5) a shot toward the base trying to focus on whether leaf stems come straight out of the ground (basal leaf) or branch off from the flower stem above ground (cauline leaf).
6) Do NOT bother posting lots of shots of the top of the flowers: one is plenty because other than color and general arrangement of the umbel they all look nearly identical. For the Computer Vision Model multiple shots are likely even detrimental because they will dominate the training set.
Guide
Cymopterus terebinthinus - except when fruiting looks a lot like a medium to large leafy yellow Lomatium with highly dissected shiny leaves with a sharp tipped leaflet. In WA state often found in dry sandy (sometimes rocky) soils and slightly sticky/shiny leaves and stems may have sand grains stuck on them. Mature fruit with multiple wing-like ridges and even during late flowering the basic ridged structure is apparent under each flower. Observation.
L. ambiguum - yellow medium small to tall lanky glabrous Lomatium with highly divided leaves mostly on floral stem and looking somehow ill-formed with irregular sized rounded lobes (reminiscent of moose antlers Observation). Flowers mid spring, no involucre or involucel (umbel bracts), umbels usually multiple and well separated when mature. Lacks short fuzzy flower stem hairs characteristic of L. triternatum, but requires good closeup photo. Observation.
L. brandegeei - montane, medium to largish, deeply divided leaves, medium to narrow width leaflets with highly visible veination, yellow flowers, very common in developed serpentine soil in Wenatchees (and more widely in dry side central to northern Cascades) despite being listed as vulnerable. Observation and Observation.
L. canbyi - often on shallow lithosol, small early flowering white with distinctive widish leaflets, usually glaucous/grayish/bluish and held close to flat in plane of leaf, often quinate division, often with a tiny cusp on leaflet tip. Contrary to Burke, I find the involucel lobes are often quite prominent, but sometimes thin and whispy. Flower stems usually brownish red. Mature fruits very flattened and green with red edges (eventually brown). Observation and Observation.
L. columbianum - large and bushy with rosy-pink flowers, unmistakable when in flower and even after. Observation and Observation.
L. cous - small yellow, not yet observed by me. Found in the southeast corner of Washington (and elsewhere). Burke.
L. cuspidatum - serpentine specific, distinctive leaves, purple flowers. Mature fruits somewhat flattened but have no wings or narrow wings. Detailed description.
L. dissectum (Fernleaf) - large bushy, dark red/purple (sometimes yellow) flowers, wider leaflets than L. multifidum. Observation.
L. farinosum - very early flowering, often on shallow lithosol, very small yellow (or white?) glabrous with narrow branched leaves. Distinctive leaves with each side branch in three parts (biternate), linear leaflets folded into V- to U-shaped cross-section, sometimes flattened out some when older. At maturity most leaflets have a tapered reddish/brown tip (Observation, also found in L. triternatum). Involucel lobes prominent and often fused at bases. Mature fruits somewhat flattened but have narrow wings. All the ones I have seen are on scabland (shallow lithosol) where they can be locally abundant. Observation (early) ; Observation (late).
L. geyeri - medium small, white flowers with fairly narrow leaflets, larger and more leaves than L. gormanii and usually growing in deeper soil. Has a distinctive double root bulge (Burke). I am fairly sure this also common in the eastern Wenatchees in exposed sites. Observation.
L. gormanii - very early flowering, widespread tiny plant, white flowered, glabrous, with no flower stem leaves (unlike piperi), sometimes locally abundant on shallow lithosol. Mature fruits somewhat flattened but have very narrow wings. Observation.
L. hallii - small to medium, yellow flowers, found in Oregon including Siskiyous. Observation.
L. howellii - uncommon, distinctive wide toothed leaflets, mostly on Klamath serpentine. Observation.
L. klickitatense - large puffy finely dissected, leaflets longer than L. papilioniferm, yellow flowers. Observation and Observation.
L. knokei - very rare medium small yellow with narrow leaflets. Possible observation.
L. laevigatum - very narrow range mostly in Columbia Transect, large yellow with long leaflets, involucel nearly absent. Observation.
L. leptocarpum (L. bicolor leptocarpum) - not yet observed by me. Observations by others.
L. linearifolium - very similar to L. gormanii, main obvious difference is elongated flower head. I have not observed this one. Mostly in southeastern WA. Burke.
L. lithosolamans - very early flowering white, on shallow lithosol, uncommon but possibly locally abundant on extreme lithosol, usually with very few leaflets that are V-shaped in cross section unlike other early salt and peppers. Leaves few and rather fleshy and often persist and retain shape until completely dry and brown. Flower umbel sometimes elongated rather than flat on top. Fruits ridged but lacking obvious wings, usually turning purplish near maturity. Endemic to Kittitas/Yakima Counties. Observation by kimberlyq and (fruiting/dried leaves) observation.
L. macrocarpum - widespread, sometimes on shallow lithosol, medium sized, ground hugging when in flower (later more erect and when in fruit the stems are often very erect, towering over the shriveling leaves), easily recognized green-white flowers with long white anthers (often yellow flowers further south), velvet-hairy floral stalks and bracts, cusped leaflet tips, sometimes has quinate leaf division, ASYMMETRIC secondary umbel bracts (involucels) longer on outer hemisphere. Observation.
L. martindalei - wet montane, small, usually prostrate, wide leaflets, yellow flowers. Observation.
L. multifidum (Carrotleaf) - large bushy highly dissected leaf, dark red or yellow flowers, very similar to L. dissectum but narrower leaf segments (?). Observation.
L. nevadense - central to southern Oregon and further east and south, somewhat similar to canbyi.
L. nudicaule - sometimes montane, medium to large, unmistakeable very broad leaflets, yellow flowers, large swollen base where umbels branch. Observation.
L. papilioniferum - large showy yellow flowered (smaller in stunting habitats), distinctive highly dissected leaves with short terminal leaflets, dissections appear angular, leaves often rough looking or with very short hairs. Foliage looks "frothy" from a distance. One of few on rock cliffs, extremely common in Columbia transect. Observation.
L. piperi - see L. gormanii. Tends to be at higher elevations (I think) and more often on clay soils. If there are many plants locally, digging up a root distinguishes - piperi has many rootlets on the globose tuber. Observation.
L. quintuplex - on shallow lithosol, small yellow flowered with highly dissected leaves in a strongly 3-D shape and slightly cusped nearly cylindrical leaflets (photo), in marginal rocky sites where it is often very abundant. Mature fruits somewhat flattened but have no wings or narrow wings. Narrow range in Kittitas and Yakima counties. Observation.
L. refugianum - not yet published. Looks as if it will be yellow flowered, highly dissected glaucous leaves with short thick leaflets. Type locality Bethel/Burnt Mountain Ridge east of Mt. Rainier. Observation by others.
L. roneurum - distinctive leaves, narrow range on Chumstick and adjacent gneiss rocks. Observation and Observation.
L. simplex - hard to distinguish from narrow-leaved forms of L. triternatum. lanky medium sized yellow, two to three times ternate narrow leaflets, often very long leaflets. Velvet-like hairy. Does NOT have stem leaves (unlike many triternatum). Observation.
L. thompsonii - narrow endemic in Wenatchee Mountains. Medium to large bushy yellow, elongated fruits. Rather lacy looking with highly dissected (branched) leaves and narrowly flat leaflets. Very short hairs on all stems and fruit.Mostly in East Wenatchee mountains above Wenatchee in Blewett Pass to Stuart Ridge area. Can be confused with L. brandegeei or L. multifidum. Observation.
L. triternatum - highly variable in size and leaflet width (more a species complex than a single species). Very common east of the Cascade ridge. Small to medium sized, yellow to pale yellow, narrow leaflets (narrowly lanceolate to nearly linear, except broader in var. brevifolium). Narrow-leafed forms hard to distinguish from L. simplex. Dense short hairs on rachis and flower stem (rather hard to see because they are so short), sometimes has reduced leaf on flower stem (unlike simplex), often disorganized looking leaves, lacking the specific 3-D structure found in many Lomatiums. Observation.
L. tuberosum - on coarse basalt talus/scree, rare adorable plant, very distinctive terete foliage often with bluish color, dark yellow flowers. Observation and immature fruits.
L. utriculatum - small lowland coastal, yellow flowers early spring, highly dissected leaves with narrow leaflets. Observation and umbel details.
L. watsonii - small yellow to pale yellow flowered, often hairy leaves, somewhat similar to L. canbyi and L. cous (found only in SE corner). Mostly from Wenatchee Mountains to south central WA often among large rocks or on rocky soil. Leaves nearly glabrous or with dense short hairs. Partially or fully fused involucel. Burke. Observation.
Lomatium nova 1 - nudicaule-like https://www.inaturalist.org/observations/219212523
Lomatium (possible) nova 2 - knokei-like https://www.inaturalist.org/observations/218263367
