'Appar' Flax Release: Origin, Distinguishing Characteristics, and Use; and a Native Alternative

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This article summarizes information on the taxonomy of 'Appar', a perennial blue flax cultivar (Linum perenne L. [Linaceae]), and characteristics that distinguish it from native Lewis flax (Linum lewisii Pursh [Linaceae]). 'Appar' apparently originated as a European flax that escaped from garden cultivation. Randomly amplified polymorphic DNA (RAPD) analysis places 'Appar' with other collections of European Linum perenne and separates it from native North American collections of Lewis flax. Morphologically, 'Appar' differs from Lewis flax in having an intense blue petal color, shorter internodes, leaves that point upward along the stem, and multiple slender stems suffused with red near the base. The heterostylous reproductive system, which it shares with its European cousins, keeps 'Appar' reproductively isolated from native populations of Lewis flax. All available data indicate that 'Appar' is not invasive and does not pose a threat to native flax populations. Ease of establishment, seed production, and showiness of the abundant flowers recommend 'Appar' for use in xeriscape plantings. Alternatively, the recent germplasm release of Lewis flax, 'Maple Grove', also establishes readily from seed and can be effectively used when objec- tives dictate the exclusive use of native germplasms.

Pendleton RL, Kitchen SG, McArthur ED, Mudge jE. 2008. The 'Appar' flax release: origin, distinguishing characteristics, and use; and a native alternative. Native Plants Journal 9(1):18-24.

heterostyly, distyly, native plants, revegetation, xeriscaping, Linum lewisii, Linum perenne, Linaceae

8 USDA NRCS (2007)

NATIVEPLANTS 19 1 1 1 SPRING 2008 orbs are important components ters. It occurs across a range of habitats, (Figure 2). Heterostyly is a plant repro- of plant communities. They con- from semiarid desert shrubland to mon- ductive system, thought to promote out- tribute to biodiversity, often tane forest and meadows, throughout the crossing, in which populations consist of accounting for the majority of plant western half of North America. Lewis flax 2 (distyly) or 3 (tristyly) plant morphs species richness (Pokorny and others provides spring forage for deer, offers that differ in the relative heights of their 2004). They resist the expansion of seeds for birds and small mammals in fall stigmas and anthers (Barrett 1990). Suc- functionally similar herbaceous weed and winter (Howard and Jorgensen 1980; cessful seed production requires deposi- populations and provide critical habitat Stevens and Monsen 2004), and con- tion of pollen from an alternate plant needs for native wildlife (Shaw and oth- tributes to the aesthetics and biodiversity morph. Taxonomic descriptions of ers 2005). Despite the importance of of plant communities. The 'Appar' culti- Lewis flax, however, characterize it as forbs to ecosystem stability and habitat, var possesses many characteristics that homostylous, having only long-styled few native forbs have been developed for make it useful for ornamental plantings, plants. Furthermore, homostyly is the commercial release (McArthur 1988; roadside stabilization, wildlife habitat key characteristic distinguishing Lewis Shaw and others 2005). improvement, and in wildland restora- flax from Linum perenne L. (Linaceae), a In 1980, the Soil Conservation Ser- tion plantings (Howard and Jorgensen blue-flowered perennial flax found vice released the 'Appar' cultivar for 1980; ltchen 2002). 'Appar' has good throughout Europe. commercial production of seed to be seedling vigor, establishes easily, produces The observation that the 'Appar' cul- used in restoration plantings (Howard abundant seeds, and is widely adapted. tivar is heterostylous posed numerous and Jorgensen 1980). At the time of The deep blue color of the petals and the questions regarding the origin and use release, the germplasm was believed to plants' drought tolerance make it attrac- of the 'Appar' germplasm. Did 'Appar' be a selection of the North American tive as an ornamental for xeriscaped gar- represent a reproductive variant of Lewis flax (Linum lewisii Pursh dens (McArthur 1988; Figure 1). native Lewis flax, or was it a nonnative [Linaceae]). Lewis flax is a relatively In 1989, we observed that 'Appar' flax? Is Lewis flax a valid species?Taxon- short-lived perennial forb with showy plants growing outside the Shrub Sci- omists disagreed on placement of Lewis blue flowers borne in open cymose clus- ences Laboratory were heterostylous flax within the Linum perenne complex; 19

NATIVEPLANTS 19 1 1 I SPRING 2008 some regarded Lewis flax as a separate species (for example, Kearney and Pee- bles 1969; Martin and Hutchins 1980; Cronquist and others 1997), while others considered Lewis flax as a subspecies of Linum perenne (for example, Munz 1968; McGregor and others 1986; Welsh and others 1993; Kartesz and Meacham 1999). Concerns were also raised regarding possible expansion of 'Appar'

plantings into native communities and 7> subsequent introgression of 'Appar' genes into naturally occurring populations of Lewis flax (Kitchen 2002).

Figure 1. 'Appar' Lewis flax plants growing in front of the Shrub Sciences Laboratory in Provo, Utah. photo by RL Pendleton In a recent report (Pendleton and others Distyly 2008), we present results from morpho- metric, genetic, and pollination studies using seed collections of known North American, European, and 'Appar' sources. In this study, we grew plants of 9 European, 9 North American, and 3 'Appar' seed sources. European accessions were obtained from botanical gardens in Europe and represented collections of both wild and cultivated plants from Austria, Belgium, Finland, Germany, Poland, Hungary, and the Czech Republic. Eight of the collections short-styled long-styled were of Linum perenne and one was of Linum austriacum, a close relative within the L. perenne complex. North Figure 2. Diagram depicting reciprocal anther and stigma heights of distylous Linum perenne. American collections made by S Successful seed production requires pollen transfer between alternate plant morphotypes Kitchen came from populations of (arrows). diverse topography and elevation located in South Dakota, Washington, Colorado, Nevada, and Utah. 'Appar' sources were grown from certified 'Appar' seed and from 2 maintained seed lines. The Black Hills seed line is the putative source for 'Appar'. The Montana seed line is virtually identical, causing some uncertainty as to which gave rise to 'Appar'. We measured 18 morphological variables on 10 plants grown from each seed collection and examined genetic relatedness of the dif- ferent collections using randomly

NATIVEPLANTS 19 1 1 I SPRING 2008 THE 'APPAR' FLAX RELEASE amplified polymorphic DNA (RAPD) gin and likely escaped from garden culti- an average stamen length of 7.1 mm analysis. We also performed self- and vation somewhere in the northern plains (0.28 in). At higher elevations and lati- cross-pollinationswithin and among seed states near South Dakota. tudes, however, the distance between source groups. We concluded that Lewis stigmas and anthers may be less than is flax fulfills most definitions of a unique reported above (Mosquin 1971). Stig- species, separate from other European mas in Lewis flax are linear in shape members of the perennial blue flax (Figure 4C). Additionally, the petal color (Linum perenne) complex. Lewis flax of 'Appar' plants is consistently of a deep accessions were reproductively isolated When in flower, 'Appar' plants can read- blue, whereas flower color in Lewis flax and distinct both morphologically and ily be distinguished by the reproductive varies considerably, ranging from near genetically from perennial blue flax col- system. 'Appar' plants are of 2 types, des- white through lavender to blue (Figure lections. 'Appar' plants were morphologi- ignated long-styled and short-styled. 5). In our study, 2 of 9 native flax collec- cally similar to smaller-statured European Long-styled plants have style lengths of tions were blue (Larimer County, Col- collections and fully interfertile with about 7.5 mm (0.3 in) and stamen orado, and Sanpete County, Utah), them. Cross-pollinationsbetween 'Appar' lengths of 4.5 mm (0.18 in). Short-styled whereas one from Clark County, Neva- and North American sources yielded only plants have the opposite configuration, da, was nearly white. The other 6 collec- 2 potentially viable seeds (seeds were not with average style lengths of 4.8 mm tions were predominantly lavender. germinated) from a possible 920 (0.2%). (0.19 in) and stamen lengths of 7.1 mm Experience indicates that dry-site collec- UPGM clustering of RAPD data (Figure (0.28 in; Figure 4A, B). Also, the shape of tions of Lewis flax tend to be lightest in 3) shows a distinct separation of the the stigmatic surface in 'Appar' plants is color, while those from higher elevations North American and European sources, rounded or capitate. Lewis flax plants and latitudes have deeper color. with 'Appar' plants clustering amid Euro- are all long-styled (longer even than Heterostyly is most often associated pean sources. These data demonstrate long-styled 'Appar' plants), with an aver- with genetic self-incompatibility (Bar- that the 'Appar' release is of European ori- age style length of 10.9 mm (0.43 in) and rett 1990). Homostylous North Ameri-

ROSEMARY L PENDLETON AND OTHERS NATIVEPLANTS 19 1 1 I SPRING 2008 Appropriate use of any flax seed requires that the seed source be properly identified. Seeds of 'Appar' origin have been used in native plant gardens and in research studies in the belief they were native Lewis flax. A few companies continue to market 'Appar' as "native" Lewis flax. Consequently, care must be taken regarding the true source of seeds cur- rently labeled as Lewis flax (L. lewisii or L. perenne ssp. lewisii). Seed producers should designate seeds from the 'Appar' source as perennial blue flax (Linurn perenne). Source-identified native flax seeds should be designated as Lewis flax (Linum lewisii). A new Lewis flax germ-

Figure 3. Phenogram produced using UPGMA clustering analysis (NTSYS-pc, Rohlf 1993) for plasm release, 'Maple Grove', is now 29 bulked or individual tissue samples of flax. Bulked North American population samples are available for situations where the use of depicted in blue, bulked European population samples are in red, and individual plants of native plant material is desired (Kitchen putative 'Appar' sources are in green. 2006). 'Maple Grove' was selected from a series of 19 North American Lewis flax can Lewis flax is self-fertile, in our study Seeds of 'Appar' can be distinguished accessions for its seedling vigor, drought producing an average of 8 seeds per fruit from native Lewis flax seeds by both size tolerance, plant longevity, rust resist- out of a possible 10. In contrast, hand- and weight, being smaller and lighter in ance, and seed production (Kitchen pollinations of 'Appar' flowers using self weight. In the above-mentioned study, we 1995,2006).It is considered comparable pollen produced no viable seeds. determined that mean seed length (n = to 'Appar' in establishment success and 'Appar' plants tend to be shorter than 30) for 'Appar' was 3.3 mm (0.13 in) and plant vigor but produces fewer flowers most native collections, having shorter mean seed width was 1.9 mm (0.07 in). and seeds per plant. Consequently, internodes, upright leaves, and multiple Seed sizes for Lewis flax varied with popu- 'Appar' may continue to have a place in stems that are suffused with red near the lation, with mean lengths ranging from revegetation of areas where color, diver- base. Lewis flax plants have longer intern- 3.5 to 4.6 mm (0.14 to 0.18 in; n = 10 per sity, and ecosystem stabilization are pri- odes, reflexed leaves, and fewer, thicker population), and mean widths ranging mary considerations, and the exclusive stems. A classification program using 11 from 1.9 to 2.4 mm (0.07 to 0.09 in). Seed use of native seeds is not mandated. morphological variables (Breiman and weights for 'Appar' accessions ranged The discovery of a heterostylous others 1984; Therneau and Atkinson from 29 to 36 mg for 25 seeds (690 000 to reproductive system in 'Appar' plants 1997) selected petal color as the most 860 000 seedslkg [ 1900 000 to 1520 000 and subsequent determination of a important distinguishing character, fol- seedsllb]),whereas North American acces- European origin raised concerns over lowed by leaf angle. Petal color alone cor- sions ranged from 39 to 67 mg for 25 seeds the possible unintended spread of rectly classified 93 (88% of the 106-plant (640 000 to 373 000 seedslkg [ 1410 000 to 'Appar' into native communities and the total) of the 30 'Appar' and 76 Lewis flax 825 000 seedsllb]). 'Appar' seeds also have subsequent introgression of 'Appar' plants. Leaf angle correctly classified 92% a pronounced "hook" at the radicle end genes into native flax populations. of the plants. Five of the Lewis flax plants that may or may not be present in seed These concerns prompted members of that were incorrectly classified using leaf collections of Lewis flax (Figure 6). the Colorado Weed Management Asso- angle were from a collection taken from ciation (CWMA) to consider listing Elk Knoll, Sanpete County, Utah. Most of 'Appar' as a noxious weed (Kitchen the plants from this collection appeared 2002). A workshop organized by the to be in poor health, a fact that may have CWMA in 2000 resolved many concerns 22 affected leaf position. resulting in the near-unanimous con-

NATIVEPLANTS 1 9 1 1 I SPRING 2008 THE 'APPAR' FLAX RELEASE clusion that 'Appar' was not invasive and should be removed from the CWMA handbook. Some concern over introgression still remained, however. Our data from cross-pollination experiments demonstrate almost total reproductive isolation between 'Appar' and native Lewis flax, with only 2 potentially viable seeds produced from a possible 920. A further investigation of possible gene ex- change examined linear-simple-sequence repeat DNA markers (ISSRs) and morphological characteristics of sympatric indigenous Lewis flax and seeded 'Appar' (Johnson and others 2006). This recently completed field study found no evidence of hybridization. Therefore, we conclude that established plantings of 'Appar' should not pose a threat to the genetic integrity of native flax populations.

Barrett SCH. 1990. The evolution and adap- tive significance of heterostyly. Trends in Ecology and Evolution 5:144-148. Breiman L, Friedman J, Olshen R, Stone C. 1984. Classification and reqression- trees. Fiqure 4. Flowers of native North American Lewis flax and the 'Appar' blue flax release show- Pacific Grove (CA): Wadsworth. 358 p. in> relative positions of anthers and stigmas. Long-styled '~~~ar'~lant(A). Short-styled 'Appar' plant (B). Long-styled North American plant (C). Note differences in the shapes of the Cronquist A, Ho'mgren NHf Holmgren PK. stigmatic surface (arrows). motor by RL Pendlefon 1997. Intermountain flora, vol 3, part A. Subclass Rosidae (except Fabales). New York (NY): New York Botanical Garden. 446 p. Howard CC, Jorgensen KR. 1980. 'Appar' Lewis flax (hum lewisii Pursh) descrip- tion, adaptation, use, culture, management, and seed production. Aberdeen (ID): USDA Soil Conservation Service, Plant Materials Center. 4 p. Johnson LA, Price TM, Woolstenhulme LA. 2006. Genetics and introgression of wildland forb populations and seedings. Final report submitted to Durant McArthur of a joint researchfcooperative agreement between the USDA Forest Service, Rocky

Mountain Research Station, Shrub Sci- Figure 5. Lewis flax populations show variation in the color of their petals. photo by RLPendleton ences Laboratory and Brigham Young University, Provo, Utah. 22 pp.

ROSEMARY L PENDLETON AND OTHERS NATIVEPLANTS 1 9 1 1 I SPRING 2008 Therneau TM, Atkinson EJ. 1997. An intro- duction to recursive partitioning using the RPART routine. Technical Report Series No. 61. Rochester (MN): Department of Health Science Research, Mayo Clinic Technical Publication 61. 52 p. [USDA NRCS] USDA Natural Resources Con- servation Service. 2007. The PLANTS Database. URL: http://plants.usda.gov (accessed 17 Jan 2007). Baton Rouge (LA): National Plant Data Center. Figure 6. Seeds of 'Appar' (left 2 seeds) compared with seeds from the new 'Maple Grove' Welsh SL, Atwood ND, Higgins LC, Goodrich Lewis flax release (right 2 seeds). photo by~nneloria S. 1993. A Utah flora. Provo (UT): Brigham Young University. 986 p. Kartesz JT, Meacham CA. 1999. Synthesis of Mosquin T. 1971. Biosystematic studies in the the North American flora, version 1.O. North American species of Linum, section Chapel Hill (NC): North Carolina Botani- Adenolinum (Linaceae). Canadian journal cal Garden. CD-ROM. of Botany 49:1379-1388. Kearney TH, Peebles RH. 1969. Arizona flora. Munz PA. 1968. A Flora of California. Berkeley Berkeley (CA): University of California (CA): University of California Press. 1681 p. Press. 1085 p. Pendleton RL, Kitchen SG, Mudge 1, Kitchen SG. 1995. Return of the native-a McArthur ED. 2008. Origin of the flax look at select accessions of North Ameri- release 'Apparf and its taxonomic position can Lewis flax (Linum lewisii). In: Roundy within the Linum perenne L. complex. BA, McArthur ED, Haley JS, Mann DK, International Journalof Plant Sciences 169 compilers. Proceedings, wildland shrub (3):445-453. and arid land restoration symposium; Pokorny ML, Sheley RL, Svejcar TJ, Engel RE. 1993 Oct 19-21; Las Vegas, NV. Ogden 2004. Plant species diversity in a grassland (UT): USDA Forest Service, Intermountain plant community: evidence for forbs as a Research Station. General Technical critical management consideration. West- Report INT-GTR-315. p 321 -326. ern North American Naturalist 64:219-230. Kitchen SG. 2002. Lewis flax-native or Rohlf FJ. 1993. NTSYS-pc. Numerical taxon- exotic-cultivar or weed: implications for omy and multivariate analysis system, ver- germplasm development. Certified Seed sion 1.80. Setaudet (NY): Applied Biosta- Gleanings 21 5-6. tistics Inc. Kitchen SG. 2006. Release of Maple Grove Shaw NL, Lambert SM, DeBolt AM, Pellant M. germplasm Lewis flax. Certified Seed 2005. Increasing native forb seed supplies Gleanings 21 5-6. for the Great Basin. In: Dumroese RK, Riley Martin WC, Hutchins CR. 1980. A flora of LE, Landis TD, technical coordinators. New Mexico, vol 1. Stuttgart (Germany): National proceedings, forest and conser- J Cramer. 1276 p. vation nursery association-2004. Fort McArthur ED. 1988. New plant development Collins (CO): USDA Forest Service, Rocky in range management. In: Tueller PT, editor. Mountain Research Station. Proceedings Vegetation science applications for range- RMRS-P-35. p 94-1 02. land analysis and management. Boston Stevens R, Monsen SB. 2004. Forbs for seed- (MA): Kluwer Academic Publishers. p ing range and wildlife habitats. Chapter 81-1 12. 19. In: Monsen SB, Stevens R, Shaw NL, McGregor RL, Barkley TM, Brooks RE, compilers. Restoring western ranges and Schofield EK, editors. 1986. Flora of the wildlands, vol 2. Fort Collins (CO): USDA Great Plains. Lawrence (KS): University Forest Service, Rocky Mountain Research Press of Kansas. 1402 p. Station. RMRS-GTR-136-vo1.2. p 425-466.

NATIVEPLANTS 1 9 1 1 I SPRING 2008 THE 'APPAR' FLAX RELEASE