Tuesday, June 12, 2012

Lomatium ravenii, Hunzinger Flat, Lassen County, California?

NDDB EO#32 Lomatium ravenii at this site was reported in first in 2003, without citation of a voucher specimen, and without any subsequent revisits.  On June 6, 2012 I visited the site, and having also visited the type locality for L. ravenii (1 mile S of Ravendale) and nearby sites, am uncertain of the taxon of Lomatium present at NDDB EO#32 (1/4 mile N Hunzinger Flat, Lassen County, 41.09199 - 120.78617)

Lomatium ravenii was described by Mathias & Constance (1959).  It was treated as distinct by Constance (1993).  Cronquist (1997), however, did not recognize L. ravenii: rather, he submerged it within a wholesale variable and geographically widespread L. nevadense (with a geographic range over most of the northern Great Basin).

At the type locality of L. ravenii, and at nearby reported sites on the Madeline Plains, Lassen County, plants answering to L. ravenii have leaves that are subtly but distinctly different from the plants at  NDDB EO#32, being more finely dissected [that is, upon morphometric analysis, cf.  Carlson et al. 2011, would a) show a greater bifurcation ratio, and b) would have linear, fewer lobed terminal leaflet segments as compared to topotype material of L. ravenii).  Published manuals use flower color to distinguish taxa of Lomatium, and because these plants flower very early (often before regional road networks are passable and snowfree) flower color is often not evident on herbarium specimens.  The plants at NDDB EO#32 did not have purple flowers, but because flower color fades quickly in the yellow flowered taxa, such that spent flowers of both yellow and white flowered taxa appear similar in senescence, flower color of NDDB EO#32 was not evident on my visit. (I will also comment here than central Nevada material at NY attributed does not match the type of L. ravenii, and is probably undescribed)

Taxonomy of Great Basin Lomatium allied to L. nevadense is not resolved.  Lomatium ravenii has been attributed to a range across most of the central Great Basin (Constance & Weatherwax 2012).  However, plants allied to this group from eastern Oregon have been shown to be a distinct species, L. bentonitum (Carlson et al. 2011).

My specimen of NDDB EO#32 is more similar in leaf morphology to L. foeniculaceum var. macdougalii, as treated in TJM2 (Constance & Weatherwax 2012), at least compared to material attributed to this taxon from near Alturas, and material from central Oregon.  There is a unprocessed record for L. ravenii for the Lane Reservoir quadrangle, and if a second site is known, would be important to voucher if appropriate.  Notable in this regard that many reported occurrences of L. foeniculaceum var. macdougalii and L. ravenii from Modoc and Lassen counties are not vouchered.

A salient habitat difference pertaining to site occupancy for L. foeniculaceum var. macdougalii versus L. ravenii is related to substrate.  Lomatium ravenii, at least the type population, and other populations on the Madeline Plains, occur on fine, clay and silt, subalkaline lacustrine and aeolian deposits that form deep soils on sites that are seasonally flooded in the exceptional, infrequent wet year (see photo on Calphotos).  By contrast, L. foeniculaceum var. macdougalii occurs on tehpra deposits (material that falls out of the air associated with explosive vulcanism events).  At NDDB EO#32 the deposit is a volcaniclastic tephra that was entrained within a mudflow,  which subsequently set.  The parent material at the site has weathered sufficiently to have a high clay component in the soil.  However, the site is not subalkaline, but rather the soils are slightly acidic.   By contrast, the soil pH at sites I visited for L. ravenii ranged from 7.5 to 8.1 .  This habitat contract is suggestive that the plants at EO#32 are L. foeniculaceum var. macdougalii rather than L. ravenii.

It should be noted here that the revised Jepson Manual treatment attributed to Lincoln Constance was not extensively changed from his 1993 treatment (since he was not active by 1999 and died in 2001).  That fact posits the problem that some California endemic taxa would benefit from additional study, which, along with the recent description of other novel, narrowly endemic, rare taxa of Lomatium from the arid western U.S. (Helliwell 2010, Darrach & Wagner 2011, Darrach et al. 2011),  suggests further study of the entire genus is suggested, and that determination of the distribution and occurrence of rare taxon of Lomatium in northeastern California is far from resolved (cf. Soltis & Novak 1997, Gitzendanner & Soltis 2001).

Constance, L. and M. Weatherwax. 2012.  Apiaceae, in B.G. Baldwin et al. [Eds.], The Jepson Manual, Vascular Plants of California .  Univ. California Press.

Constance, L. 1993.  Apiaceae, in J.C. Hickman [Ed.], The Jepson Manual, Vascular Plants of California .  Univ. California Press.

Cronquist, A.  1997.  Lomatium, pp. 394-420 in A. Cronquist, N.H. Holmgren & P.K. Holmgren.  Intermountain Flora Vol. 3A.  New York Botanical Garden.

Carlson, K.M., D.H. Mansfield & J.F. Smith.  2011.  A new species in the Lomatium foeniculaceum (Apiaceae) clade revealed through combined morphometric and phylogenetic analysis.  Systematic Botany 36(2):495-507.

Darrach, M., K.K. Theib, B.L. Wilson, R.E. Brainerd and N. Otting.  2011.  Lomatium tamanitchii (Apiaceae), a new species from Oregon and Washington state, U.S.A.  Madrono Vol. 58.

Darrach, M. & D.H. Wagner. 2011.  Lomatium pastoralis (Apiaceae), a new narrow endemic species from Northeast Oregon.  J. Bot. Research Institute Texas 5(2):427-435.

Gitzendanner, M.A. and P.S. Soltis.  2001.  Genetic variation in rare and widespread Lomatium species (Apiaceae): A comparison of AFLP and SSCP data.  Edinburgh Journal of Botany 58:347-356.

Mathias, M.E. & L. Constance.  1959.  New North American Umbelliferae – III.  Bull. Torrey Botanical Club 86:374-382.

Soltis, P.S. & S.J. Novak.  1997.  Polyphylly of the tuberout Lomatiums (Apiaceae): cpDNA evidence for morphological convergence.  Systematic Botany 22:99-112.

No comments: