HORTSCIENCE 55(4):595–596. 2020. https://doi.org/10.21273/HORTSCI14763-19 P. cembra (Dirr, 2009). The bark is gray- green, darkening to gray-brown, and becom- Pinus cembra ing scaly and fissured with age. Pinus cembra ‘Herman’ (Prairie is monoecious, with female cones that are ® terminal and 5 to 7.5 cm long. Male (pollen) Statesman Swiss Stone Pine): A New and female (seed) cones are not considered to have ornamental value. This species exhibits Evergreen Landscape Tree limited seed dispersal because the female cones do not open and dispersal is dependent Todd P. West, Gregory Morgenson, Larry Chaput, and Dale E. Herman on its main vector, the spotted nutcracker Department of Plant Sciences, North Dakota State University, Department (Nucifraga caryocatactes L.), in its native 7670, P.O. Box 6050, Fargo, ND 58108-6050 range (Salzer, 2011). Three-year-old mature female cones will drop in the spring, with seed Additional index words. Arolla pine, cold hardiness, low maintenance, ornamental tree, being released by birds or through decompo- Pinaceae, Quinquefoliae sition of scales (Dirr, 2009). Pinus cembra has shown to be relatively pest-resistant, including good resistance to Herman is a new cultivar of Pinus cembra cembra. These cultivars vary with needle color white pine blister rust (Cronartium ribicola L. (common names include Swiss Stone pine, (blue-green, green, yellow-green, and silver- J.C. Fisch) (Stephan, 2004). Pinus cembra Arolla pine, Swiss pine, Stone pine, or Aus- blue), growth habits (globose, conical, broad cultivars have performed extremely well dur- trian Stone pine). Its lateral branches curve upright, and narrow upright), and growth rate ing periodic drought events and received markedly upward and slightly inward, result- and size (dwarf, intermediate, and large) no foliage needle burn as a result of low ing in a narrowly erect, strikingly dense (Table 1). ‘Herman’ is ranked in the interme- winter temperatures at the North Dakota growth habit. ‘Herman’ (original selection) is diate class (15 to 30 cm per year/1.5 to 3 m State University (NDSU) Dale E. Herman 12 m in height with a spread of 4.5 m after 40 after 10 years) with respect to growth rate and (DEH) Research Arboretum (Absaraka, ND; years. Average growth is 15 to 30 cm per year size. There are two other cultivars, Aurea and lat. 46.9859, long. –97.3549). This pine spe- with typical average height of 3 m after 10 Westerstede, that are ranked in the intermedi- cies has also been reported as being tolerant years. It is adapted to USDA plant hardiness ate class with ‘Herman’; both have different of deer browsing—unlike its close relative, zones 3 to 7 and performs well on a wide range needle colors, yellow-green and blue-green P. strobus (eastern white pine) (NC State of soil types. Pinus cembra is a five-needled respectively, and different growth habits, con- Extension, 2020; WSU, 2020). pine with year-round rich-emerald-green ical and broad upright respectively, as compared color, with silvery-blue overtones. ‘Herman’ with ‘Herman’ with emerald-green foliage and Origin (Prairie StatesmanÒ) is extremely cold hardy narrow, upright form (Table 1). This distinct and drought tolerant, making it an excellent needle color, growth habit, and size, establish This Swiss stone pine was selected from an choice for an evergreen specimen planting in the uniqueness of Herman as compared with the open-pollinated seedling population from un- low-input landscapes without supplemental other Swiss Stone pine cultivars. known European origin. It was selected from a irrigation. Needles of Pinus cembra are typically stiff, population grown at the NDSU DEH Research Pinus cembra is an evergreen coniferous green-to-green-blue in color, and 5–9 cm Arboretum. This source of Pinus cembra has woody tree in the family Pinaceae within the long. Needles remain for 3 to 5 years, provid- been evaluated since 1976, with one seedling subgenus Strobus Lemmon, section Quinque- ing dense habit. First-year stem growth is being identified as uniquely different in 2002. foliae Duhamel, and subsection Strobus covered in dense, orange pubescence, becom- ‘Herman’ was selected for its rich-emerald-green Loudon. Other members of pines in the sub- ing grayish-brown in the second year. This is foliage and narrowly erect, dense growth habit, section Strobus include P. flexilis E. James unlike first-year shoots of the closely related which is unique in the intermediate growth size (limber pine), P. sibirica Du Tour (Siberian species, P. flexilis (limber pine), which is in along with the narrow upright habit (Table 1). pine), and P. strobus L. (eastern white pine). the same subgenus, section, and subsection as ‘Herman’ was selected in soils that are classified It is native to subalpine zones with elevations of 1200 to 2300 m (3500 to 7500 ft) above sea level in central Europe, from the Alps to the Table 1. Needle color, growth habit, growth rate, and size of Pinus cembra cultivars.z Carpathian Mountains, including Austria, the Cultivar Needle color Growth habit Czech Republic, France, Germany, Italy, Blue-Green (BG) Globose (G) Growth rate and size Poland, Romania, Switzerland, and Ukraine Green (G) Conical (C) Dwarfy (Farjon, 2017). Farjon (2017) reported this x species to be classified with ‘‘least concern’’ Yellow-Green (YG) Broad Upright (BU) Intermediate w status on the International Union for Conser- Silver-Blue (SB) Narrow Upright (NU) Large v vation of Nature (IUCN) Red List of Threat- ‘Algonquin Pillar’ BG NU Large ened Species. There are several other cultivars ‘Aurea’ YG C Intermediate ‘Blue Mound’v BG G Dwarf available in the commercial nursery trade of P. ‘Chalet’v BG BU Intermediate ‘Glauca Fastigiata’ BG NU Large ‘Glauca Nana’ BG BU Dwarf Ò Received for publication 3 Dec. 2019. Accepted for ‘Herman’ (Prairie Statesman ) G NU Intermediate publication 6 Feb. 2020. ‘Klein’ (Silver Whispersä)v SB BU Dwarf Published online 16 March 2020. ‘Looney Bin’ G NU Dwarf This work was financially supported in part by the ‘Pygmaea’ BG BU Dwarf U.S. Department of Agriculture (USDA), National ‘Silver Sheen’v BG BU Large Institute of Food and Agriculture, McIntire–Stennis ‘Stricta’ BG NU Dwarf project ND6216, and by the North Dakota Agricul- ‘Westerstede’v BG BU Intermediate tural Experiment Station. zCultivar information compiled from the American Conifer Society (https://conifersociety.org/conifers/ T.P.W. is the corresponding author. E-mail: todd.p. pinus-cembra/) and Iseli Nursery (https://www.iselinursery.com/). [email protected]. y2.5 to 15 cm per year, 0.3 to 1.5 m after 10 years. This is an open access article distributed under the x15 to 30 cm per year, 1.5 to 3 m after 10 years. CC BY-NC-ND license (https://creativecommons. wGreater than 30 cm per year, greater than 4 m after 10 years. org/licenses/by-nc-nd/4.0/). vMore commonly available in the commercial nursery trade.
HORTSCIENCE VOL. 55(4) APRIL 2020 595 ing winter needle burn as seen in other Pinus or landscape evaluations (NDSU DEH Re- species. ‘Herman’ has exhibited no symp- search Arboretum and landscape observa- toms of chlorosis growing on a soil pH in tions, data not reported). excess of 8.0, which is typical of other Pinus Availability. ‘Herman’ is sold under the spp. within the subgenus Strobus, such as trademark Prairie StatesmanÒ (U.S. Trade- eastern white pine (P. strobus) (Gilman and mark Reg. No. 2,935,955, registered 29 Mar. Watchson, 1994). Needles are borne in fas- 2005) and is available for nonexclusive li- cicles of five and are stiffer than white pine. censing. For more information, contact the Herman needles are emerald-green, which is NDSU Research Foundation, 1735 NDSU a unique trait because most cultivars have a Research Park Drive, Suite 124, Dept. 4400, blue-green foliage. The needles of ‘Herman’ P.O. Box 6050, Fargo, ND 58108-6050; are 7.5 to 18 cm long, which is longer than phone: (701) 231–6681. Plant material for the typical needle length, 5 to 7.5 cm for the vegetative propagation can be obtained from other species, with four silver stomatal lines. NDSU Department of Plant Sciences Woody The bark of ‘Herman’ is ornamental but Plant Improvement Program or designated not readily visible as a result of the dense nursery, subject to availability. There is a foliage. The mature bark is exfoliating, with horticultural royalty of $0.75 per plant Fig. 1. Mature Pinus cembra ‘Herman’ (Prairie Ò the outer layers being greyish-tan (RHS grey- through the NDSU Research Foundation. Statesman Swiss stone pine) showing lateral branches that curve upward with dense, rich- brown group 199A/B), with inner bark being ‘Herman’ is available from several commer- emerald-green foliage (left), and young clonal greyish-reddish-orange (RHS greyed-orange cial nurseries, including, but not limited to, planting of ‘Herman’ (right). group 177C). Iseli Nursery (Boring, OR), Oregon Pride Reproductive (pollen and seed) cones are Nurseries (McMinnville, OR), and Sester not considered to have ornamental value. Pollen Farms Inc. (Gresham, OR). cones are broadly ellipsoid-cylindrical shaped, colored orange (RHS greyed-orange group Literature Cited 166D), and measure 8 mm wide and 20 mm Anfodillo, T., S. Rento, V. Carraro, L. Furlanetto, long. Seed cones are ovoid, located terminally C. Urbinati, and M. Carrer. 1998. Tree water on branches, and colored brownish-grey (RHS relations and climatic variations at the alpine grey group 201A) at maturity. They are resin- timberline: Seasonal changes of sap flux and ous and mature 3 years after pollination. xylem water potential in Larix decidua Miller, Foliar (terminal) buds are ovate and acute Picea abies (L.) Karst., and Pinus cembra L. shaped. They are tannish-brown (RHS greyed- Ann. For. Sci. 55:159–172. orange group 165C) in color. They measure Dirr, M.A. 2009. Manual of woody landscape plants, 3 mm wide and 9.5 mm long. their identification, ornamental characteristics, Fig. 2. Close-up of lateral branches of Pinus Resistance to pest and stress. ‘Herman’ culture, propagation and uses. 6th ed. Stipes cembra ‘Herman’ (Prairie StatesmanÒ Swiss Pub. LLC, Champaign, IL. has shown to be a relatively pest-resistant Farjon, A. 2017. Pinus cembra. The IUCN Red List of stone pine) that curve upward with dense, rich- and stress-tolerant pine cultivar in long- emerald-green foliage. Threatened Species 2017: E.T42349A95684563. term trials conducted at the NDSU Re- 15 Nov. 2019.
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