ACIFIC

ORTH

WESTFOREST AND RANGEEXPERIMENT STATION

- • USDA FOREST SERVICE RESEARCH NOTE

PNW-261 October 1975

.

OBSERVATIONS ON THE RHIZOMES AND ROOTS

OF VACCINIUM MEMBRANACEUM^ _,

by

-•• Don Minore, Plant Ecologist

ABSTRACT

Rhizome occurrence and root structureof Vaca-inium membranaeeum were investigatedby hydraulic excavation. Numerous, robustrhizomes were present. Taproots were notobserved. V. membvanacewn rhizomes sproutedvigorously after a light surface fire killedthe shoots. They may be important in futurehuckleberry field management.

KEYWORDS: Huckleberry, Vaaainiwn membranacewn,root structure.

OREST SERVICE - U.S. DEPARTMENT OF AGRICULTURE - PORTLAND, OREGON

Vaccinium membranaceum Dougl.(thin-leaved huckleberry), the mostfrequently harvested Vacoinium speciesin western North America,-grows atmoderate to high elevations in themountains of British Columbia, Wash-ington, Oregon, Montana, and Idaho--usually in old burns. Its deliciouslyflavored fruits are gathered bythousands of berrypickers every year.

Unfortunately, most berry-producingareas are now reverting from old burnsto poor quality subalpine forest. Thewild huckleberry resource is dwindlingrapidly (Minore 1972). If thisimportant resource is to be preserved,tree invasion should be curtailed andthe fields managed for berry produc-tion. However, berry field managementis hindered by lack of informationabout the physiology, ecology, andanatomy of western huckleberries.Rhizome and root information isparticularly scarce.

Rhizome information has beenrecorded for several Vacainium species.The rhizomes of V. angusti-fol'iim Ait. ,the eastern lowbush blueberry, appar-ently contribute to its ability tosurvive burning at 2- to 3-year inter-vals—a practice commonly used toprune the bushes and increase yieldsin the managed blueberry fields ofeastern North America (Barker et al.1964, Black 1963, Chandler and Mason1939, Trevett 1956). Lowbush blue-berry plants also have deep taprootsthat may supply water and soil nutri-ents not available in the shallowersoil occupied by rhizomes (Hall 1957).VacGiniwn taproots have not beenreported elsewhere. However, V.pallidum Ait. (dryland blueberry)spreads to form colonies much likethose of lowbush blueberry (Darrowet al. 1944), indicating an extensiverhizome system in this southeasternUnited States species. Smith (1962)described the rhizome structure anddistribution of V. myrtilloides Mich,(velvet-leaf blueberry) and V. vitis-

idaea L. (mountain cranberry) in westernAlberta. V. myrtillus L. (dwarf bilberry)develops a vigorous rhizome system in theBritish Isles (Ritchie 1956). Chemistsin Oregon collected the roots and rhizomesof 7. parvifolium Smith (red huckleberry)and thin-leaved huckleberry and analysedthem for triterpene content, but made nomorphological observations (Sheth et al.1968).

The observations reported here wereundertaken to investigate rhizome occur-rence and general root structure in thethin-leaved huckleberry. Root systemsof three huckleberry plants growing incoarse sandy soil near Mount Adams,Washington, were hydraulically excavatedin September 1973. A'gasoline-poweredportable pump was used to force waterfrom a nearby lake through a 4-cm-diameterhose and fire nozzle. The resultingwater jet, applied progressively to anentire root system as the excavationproceeded, washed away the soil withoutdamaging roots or rhizomes. Exposedroot systems were photographed. Thesmallest system was diagramed by drawingeach rhizome and root segment in placeafter distances between forks and depthsbelow the soil surface were measured andrecorded. Root and rhizome portionswere taken to the laboratory, where theywere sectioned, stained with Safranin 0and Fast Green, and examined microscop-ically. Additional portions wereexamined after two more V. membranaceumplants were shovel-excavated nearMount Hood and on the Dead Indian Plateaueast of Ashland, Oregon, in July 1975.

Numerous, robust rhizomes werepresent in every plant excavated. Rang-ing in diameter from 1 to 3 cm, mostoccurred 8-30 cm below the soil surface.Rootlike in external appearance (fig. 1),these- rhizomes had numerous dormantvegetative buds. They revealed largecentral piths when viewed in cross section(fig. 2). Piths were not visible in crosssections of the roots (fig. 3). Thesmallest, simplest root system excavatedis diagramed in figure 4. The largest

Figure 1.—Thin-leaved huckleberry rhizomes and roots viewedfrom above. The smaller, branching structures are roots.Small, rhizomes axe best differentiated from large rootsby examining cross sections for presence or absence ofpith. '

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Figure 2.—Cross section of thin-leaved huckleberry rhizome.Note large pith and dormant bud.The bar is 5 mm long.

Figure 3.—Cross section of thin-leaved huckleberry root. Notethe absence of pith. The baris 5 mm long.

- . • .- • • ' • •

= Shoot

Rotten rhizomeremnant

1/12 scale

Figure 4.—Diagram of a simple rhizome and root system of thin-leavedhuckleberry as viewed from above. Approximate depths (cm) are indi-cated. The arrow indicates probable origin of plant. Roots lessthan 5 mm in diameter are not shown.

root system occupied an area of 8 m .Supporting 47 shoots, it was a complex,multilayered maze that included hundredsof rhizome and root branches.

No taproots were observed in theexcavated plants. However, occasionalsinker roots were found descending todepths of 70-100 cm. Rhizome branchingusually was dichotomous, but occasionalbur11ike forks were encountered wherethree or more branches diverged atrandom angles from a common origin.Proximal and distal portions of therhizome system usually were identifi-able by fork orientation--wheredichotomous branching occurred, thelaterals diverged at angles of lessthan 90°.

Neither rhizomes nor shoots wereweighed, but rhizome and root biomassappeared to be much greater than thatof the.shoots. Most of' the observed . .rhizomes were deep enough to avoiddamage from light surface fires.Indeed, similar rhizomes sproutedprolifically after a 1972 fire. Ifthe resulting shoots bear fruit in areasonable period of time, it may bepossible to enhance huckleberry vigorand control competing vegetation inthin-leaved huckleberry fields byburning them repeatedly.

LITERATURE CITED

Barker, W. George, I. V. Hall, L. E.Aalders, and G. M. Wood.

1964. The lowbush blueberry industryin eastern Canada. Econ. Bot. 18:357-365.

Darrow, George M., R. B. Wilcox, andCharles S. Beckwith.1944. Blueberry growing. USDA FarmersBull. 1951, 38 p.

Hall, I. V.1957. The tap root in lowbush blueberry.Can. J. Bot. 35(6):933-934.

Minore, Don.1972. The wild huckleberries of Oregonand Washington—a dwindling resource.USDA For. Serv. Res. Pap. PNW-143,20 p., illus. Pac. Northwest For.and Range Exp. Stn., Portland, Oreg.

Ritchie,, J. C.1956. Biological flora of the BritishIsles: Vaaoiniicm myrtillns L.J. Ecol. 44(l):290-298.

Sheth, Kirt, G. H. Constantine, Jr.,D. K. Williams, and P. Catalfomo.1968. Root triterpenes of Vaceiniimspecies. 'Phytochemistry 7(8):1379-1383.

Smith, D. W.1962. Ecological studies of Vqceiniumspecies in Alberta. Can. J. PlantSci. 42(1):82-90.

Trevett, M. F.1956. Observations on the declineand rehabilitation of lowbushblueberry fields. Maine Agric. Exp.Stn., Misc. Publ. 626, 21 p.

* * * * * * * *

Black, W. N.1963. The effect of frequency of

rotational burning on blueberry(Vacciniian angustifolium*) pro-duction. Can. J. Plant Sci. 43:161-165.

Chandler, F. B . , and I. C. Mason.1939. Pruning the low-bush blueberry,

Proc., Am. Soc. Hortic. Sci. 37:609-610.

The mission of the PACIFIC NORTHWEST FORESTAND RANGE EXPERIMENT STATION is to provide theknowledge, technology, and alternatives for present andfuture protection, management, and use of forest, range, andrelated environments.

Within this overall mission, the Station conducts andstimulates research to facilitate and to accelerate progresstoward the following goals:

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The area of research encompasses Oregon, Washington,Alaska, and, in some cases, California, Hawaii, the WesternStates, and the Nation. Results of the research are madeavailable promptly. Project headquarters are at:

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