| Hesperocyparis pygmaea | |
|---|---|
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| Hesperocyparis pygmaea at Salt Point, Mendocino, California | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Cupressales |
| Family: | Cupressaceae |
| Genus: | Hesperocyparis |
| Species: | H. pygmaea |
| Binomial name | |
| Hesperocyparis pygmaea (Lemmon) Bartel | |
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| Natural range ofCupressus pygmaea | |
| Synonyms[1] | |
List
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Hesperocyparis pygmaea, theMendocino cypress orpygmy cypress, is ataxon of disputed status in thewestern cypress genus. It isendemic to certaincoastal terraces and coastal mountain ranges ofMendocino andSonoma Counties in northwesternCalifornia. It is a variable tree, and closely related toHesperocyparis abramsiana andHesperocyparis goveniana, enough to sometimes be considered conspecific with them.
Thefoliage is a dull dark to light green color, with scale-likeleaves 1–1.5 mm long, with the leaf tips not spreading; seedlings bear needle-like leaves 8–10 mm long. Thecones are small, 11–24 mm long, and almost spherical, with six or eight scales arranged in opposite decussate pairs, with the bract visible as no more than a small lump or short spine on the scale. Theseeds are 3–5 mm long, with a pair of small wings along the sides.[2] The cones remain closed on the trees for many years, until the trees are killed by a forest fire; after the tree is dead, the cones open to release the seeds which can then germinate successfully on the bare fire-cleared ground.[3]
The Mendocino cypress differs little fromH. goveniana in morphology, with the most conspicuous difference inherbarium material being the usually glossy black seeds, unlike the dull brown seeds ofH. goveniana, but even this character is not constant, with dull brown seeds found in the southernmost populations ofH. pygmaea nearPoint Arena.[4] Preliminary genetic studies have shown some differences, with notably someplastid sequences (matK,rbcL, andtrnL) suggesting a possible closer relationship toH. macrocarpa, though other sequences confirm its close relationship toH. goveniana.[5] In cultivation together withH. goveniana, it retains a very different crown shape, with a tall slender crown, contrasting with the broad, shrubby crown ofH. goveniana; it also has darker green foliage (paler, yellow-green inH. goveniana).[4]
The largest recorded specimen is located in Mendocino County, with recorded dimensions of 43 m height, 2.13 m diameter, and 12 m crown spread, in 2000.[6]
Hesperocyparis pygmaea was first described as asubspecies byJ.G. Lemmon with the nameCupressus goveniana var.pygmaea in 1895. It was described as a species byCharles Sprague Sargent in 1901.[1] Sargent thought that the distinctness of the seeds from those ofC. goveniana definitively showed it to be a species though its growth habits and form did not make it easy to identify.[7]
Its taxonomic status is a long standing matter of dispute between botanists. In the 20th century some treatedCupressus pygmaea as a distinct species, following Sargent, including Wolf (1948),[4] Griffin & Critchfield (1976),[8] and Lanner (1999).[3] Others treated it withinCupressus goveniana as either avariety (C. goveniana var.pigmaea Lemmon)[9] or asubspecies (C. goveniana subsp.pygmaea (Lemmon) A.Camus), including Camus (1914),[10] and theJepson Manual (1993),[11] and one publication, theFlora of North America, did not distinguish it at all withinC. goveniana.[12]
The spelling of the scientific name has also been confused. Lemmon'sprotologue at varietal rank used the spellingpigm a, a typographic error hand corrected topigmaea, in the main description (BHLpage 23343470) butpygmaea in the contents (BHLpage 23343396). In raising the taxon to species rank, Sargent changed the spelling topygmaea (BHLpage 28545470), a legitimate change as a botanical name has no priority outside of the rank at which it is published (ICN Art. 11.2); this has been followed by most subsequent authors (including Camus in the first allocation to subspecific rank[1]), though a few subsequent authors have incorrectly used the spellingpigmaea at ranks other than varietal (e.g. Farjon 2005,[2] Little 2006[5]).
Disputes continued into the 2000s with Farjon agreeing that it should be part ofC. goveniana in 2005.[2] Additionally moving the new world cypress species to different genera was proposed three different times. In 2006 Damon P. Little proposed moving them toCallitropsis, but did not find wide acceptance.[5][1] In 2009 two different classifications were proposed,Hesperocyparis andNeocupressus.[1]
As of 2024[update]Hesperocyparis pygmaea is listed as the correct name inPlants of the World Online,[1]World Flora Online,[13] and the Gymnosperm Database.[6]
The Mendocino cypress is highly variable in growth form, depending on soil conditions. In thepygmy forest plant community on poor,acidic,nutrient-starvedpodsol soils with drainage impeded by aniron hardpan, it is a stunted tree from 0.2–5 meters in height at maturity. When occurring in its pygmy form, it is sometimes calledpygmy cypress. When growing on deep, well-drained soils it can be a large tree up to 30–50 meters in height and 1–2.4 m in trunk diameter. Thebark is dark gray-brown, with stringy texture, and fissured on old trees.[2]
Mendocino cypress occurs in very limited ranges within onlyMendocino County, on some of the historical lands of theYuki Native American people. In Mendocino County the occurrence is in a discontinuouscoastal terrace strip, primarily as a pygmy forest associated withbishop pine (Pinus muricata) andMendocino shore pine (P. contorta var. bolanderi). Occurrences are typically below 500 m in elevation.[11] The Mendocino County officialsoils survey states that "While not formally recognized as a major forest cover type, the coastal portion of the survey area also includes bishop pine and Mendocino cypress (pygmy) forest types".[14]
Along the Mendocino coastal terraces, whose geological age is approximately one million years, studies have been conducted of the biomass density andprimary productivity of theHesperocyparis pygmaea-dominated pygmy forest.[15] The terraces in this area extend a full five to ten kilometers inland from thePacific Ocean.
In the Mendocino cypress pygmy forests,biomass was measured to range between 1.6 and 4.4 kilograms per square meter aboveground; moreover, net primary productivity was found to measure 180 to 360 grams per square meter per annum above the ground surface. Mean below-ground values are 3.5 kilograms biomass per square meter, productivity being 402 grams per meter per annum. Theleaf-area ratio of the pygmy forest was estimated as 2.1 grams per square meter implying a high production efficiency per unit leaf area for anevergreen community (150 grams per meter aboveground ). According to Westman, productivity of theH. pygmaea forest lies within the range expected for open, drywoodlands. A similar community for which data is available is a pygmy conifer-oak scrubland in southernArizona.
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