Search

Our objective was to evaluate piperidine alkaloids as potential resistance factors in Sitka spruce, Picea sitchensis (Bong.) Carr, at risk to attack by white pine weevils, Pissodes strobi (Peck). We sampled 72 seedlings in each of two replicated field trials in the Oregon Coast Range. The seedlings were grown from open-pollinated seeds of putatively "resistant" or "susceptible" off-site parental sources. Alkaloid concentrations in bark and foliage were measured in previously unattacked trees at the time of weevil host selection. Leader mortality was evaluated in the fall to gauge actual resistance in the sample trees. Five families hador = 25% topkill and seven sustained50% topkill. Alkaloid concentrations differed significantly among families, but the major alkaloids did not appear to be functionally linked with topkill or useful indicators of resistance. However, our study design did not address all potential resistance mechanisms. Therefore, before concluding that Sitka spruce alkaloids have no influence on white pine weevils, complementary laboratory and field experiments are needed.

Analysis of seven taxanes: taxol, baccatin III, 10-deacetyltaxol, 10-deacetylbaccatin III, 7-xylosyl-10-deacetyltaxol, cephalomannine and brevifoliol in extracts from bark and foliage of pacific yew (Taxus brevifolia) showed a gradient of decreasing concentration from stem base to branch tip. This decrease is attributed to the generally higher concentration of taxanes in the phloem tissue and the decrease in inner bark thickness from base to branch tip. Analysis of taxanes extracted from stem bark and needles sampled over a growing season showed that most taxane concentrations were significantly lower in the needles than in the bark. Typically, taxane concentrations in bark increased from May through August; whereas, in needles, concentrations changed little during that period. Two exceptions were baccatin III, which in the summer reached levels equivalent to bark, and brevifoliol which increased from March to August, reaching levels in needles nine times greater than bark.

November-felled Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) logs with and without branches were left lying on the forest floor through August. In May, as the logs were being colonized by ambrosia beetles,Trypodendron lineatum (Oliv.) andGnathotrichus retusus (LeConte), the ethanol, acetaldehyde, and water concentrations in the delimbed logs were significantly higher than in the branched logs. Since both log types received the same rainfall, lower water contents in branched logs was probably the result of absorbed water being transported through the branches via capillary movement and evaporation. Lower tissue water levels could have prevented the establishment and maintenance of anaerobic conditions, thus limiting the synthesis of acetaldehyde and ethanol in the branched logs. By late August, the beetle densities in delimbed logs were 9–16 times greater than in the branched logs. Log ethanol concentrations could be a key chemical factor affecting the ambrosia beetle attack densities. Acetaldehyde concentrations in the logs also may have affected the attack densities.

Two new p-cymene based diphenols (1-2) were isolated from the heartwood of Calocedrus decurrans. Structures were elucidated by 1D and 2D NMR techniques and HRMS. Libocedroquinone (3) was also isolated as a natural product for the first time. A new system of nomenclature is proposed for description of such oligomeric p-cymene derivatives.

Tree voles are dietary specialists, feeding almost exclusively on conifer needles and bark. They reduce their exposure to conifer chemical defenses by physically removing resin ducts from many needles before ingesting the remaining tissue. The portion of needle removed differs among tree species, depending on the location of the resin ducts. To evaluate the amount of resin avoided by this behavior we removed the resin ducts from Douglas-fir, Western Hemlock, and Sitka Spruce needles and used gas chromatography to compare volatile resin concentrations in needles with and without the resin ducts removed. Needle tissues without resin ducts contained no terpenoid resin, demonstrating that tree voles can regulate the nutritional quality of their diet by controlling the amount of resin ingested. We suggest that differences in the physical structure (and possibly chemical composition of terpenes) of the needles make it difficult for voles to easily switch between tree hosts.

The bark and leaf essential oil of Umbellularia californica (Hook. & Arn.) Nutt. from west central Oregon, USA, was isolated by steam distillation and the chemical composition analyzed by GC-FID and GC-MS. The three major components in bark oil were 1,8-cineole (36.0%), α-santalene (9.3), and α-terpineol (6.9%), while those in leaf oil were umbellulone (41.0%), 1,8-cineole (22.0%) and sabinene (10.2%).

Spotted knapweed (Centaurea maculosa Lam.), an exotic member of the Compositae, infests large areas of rangeland in the northwestern United States. We assessed the impacts of infestation on a wilderness winter-spring range for elk (Cervus elaphus nelsoni Bailey), mule deer (Odocoileus hemionus Raf.), and white-tailed deer (Odocoileus virginanus Raf.) along the Selway River in Idaho and found no evidence of a large reduction in carrying capacity. We estimated cervid densities in open areas by scan sampling known area blocks. Densities in knapweed vegtation were greater than or equal to densities in areas of native bunchgrasses and sedges. Direct observation of animals and laboratory analyses of fecal and rumen samples showed spotted knapweed seedheads and rosette leaves were being eaten by all cervid species. Deer ate large amounts of rosette leaves at times in contrast to elk, which consumed them frequently, but in small amounts. Seedhead consumption was greatest during periods of snow cover. We collected composite samples of knapweed times and determined energy and protein content wtth standard laboratory techniques. Energy and protein content of rosettes was near that of preferred native food plants. Seedheads, while less nutritious than rosettes, remained easily obtainable above the snow. The amount of energy and protein available on sample plots decreased modestly at most after infestation. In composite samples of spotted knapweed the content of cnicin, a sesquiterpene lactone in aerial tissues, was determined by high performance liquid chromotography. Changes in cnicin levels did not appear to be responsible for seasonal changes in the amount of knapweed in cervid diets. When estimating or predicting carrying capacity of a cervid range, spotted knapweed should be considered a potential food.

In 1970 a xeric form of mountain big sagebrush (Artemisia tridentata ssp. vaseyana (Rydb.) Beetle) was reported in west central Idaho. Observations of morphology, habitat, and ecology, and analyses of foliage chemical components, clearly indicate these plants represent a new subspecies (xericensis) in the big sagebrush complex. It grows at lower elevations, 762-1,524 m (2,500-5,000 ft) and drier environments, 305-560 mm (12-22 in) precipitation, than most mountain big sagebrush, and is found on basaitic foothill soils often in association with bluebunch wheatgrass (Agropyron spicatwn (Pursh) Scribn. & Smith). In addition to soil type, the radiate growth form and a more branched paniculate inflorescence are 2 morphological characteristics useful in separating ssp. xericensis from ssp. vaseyana. It contains higher concentrations of crude protein (10.4%), phosphorus (0.3%), and total volatiles, and lower concentrations of tannins and total phenols than mountain big sagebrush. Distinct chromatograms were obtained for both subspecies when extracts were analyzed by gas and high performance liquid chromatography. Leaf morphology and fluorescence of leaf water extracts are useful characters for separating ssp. xericensis from ssp. tridentata. The chemical data, in combination with morphology and ecology, suggest this new subspecies was initially derived by hybridization of ssp. tridentata and ssp. vaseyana.

The sesquiterpene lactones isolated from species in the genus Artemisia have been reviewed in an attempt to better understand the phylogeny and systematics of the four sections (subgenera), Abrotanum, Absinthium, Dracunculus and Seriphidium, proposed by Besser in 1829. The absence of hair on the receptacle is the only morphological characteristic separating species of Abrotanum from the species of Absinthium. There are no chemical characteristics segregating the species in these two subgenera since both produce eudesmanolides and guaianolides that are identical or biosynthetically similar. This suggests that the two subgenera could be combined into one (Artemisia) as proposed by Poljakov. The subgenus Seriphidium is composed of two geographical groups, one in the Old World and the other in the New World. The Old World species almost exclusively produce sesquiterpene lactones in the eudesmanolide class whereas the New World species (section Tridentatae) produce eudesmanolides and guaianolides, many of the latter being identical or structurally related to the sesquiterpene lactones in New World Abrotanum species. The chemical data in conjunction with geographic distributions suggest that the subgenus Seriphidium is polyphyletic and that the section Tridentatae originated from Abrotanum. Consequently, the Tridentate should be recognized as a subgenus separate and distinct from the Old World Seriphidium. There was insufficient information from the subgenus Dracunculus for interpretation.

SynopsisFindings from the first two years of a long-term study of conifer log decomposition are presented. Log decomposition is regulated by the physical and chemical states, and development of decomposer foodwebs. The functional group with the greatest initial effect on the log is the channelisers, represented in our study by ambrosia and bark beetles. They not only create multitudes of channels into the logs but vector the initial decomposer community. Ambrosia beetles exclude certain elements of the decomposer community from channels until they vacate the log, at the end of their reproductive phase. The foodweb during the early stages of decomposition includes nitrogen-fixing and other bacteria, fungi, protozoa, nematodes, and arthropods. Seasonal fluctuations of temperature and moisture are hypothesised to work in tandem to modulate the activities of the decomposer community.

Concentrations of extractable total phenols and tannins have been analyzed in the outer bark, inner bark, sapwood, and heart wood from logs of four conifer species, after 1 year on the ground. To estimate decay rates, initial tissue densities were compared with those after 1 and 2 years of decomposition. The four species studied, Pacific silver fir (Abiesamabilis Dougl. ex Forbs), western hemlock (Tsugaheterophylla (Raf.) Sarg.), Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), and western red cedar (Thujaplicata D. Don) represent a gradient of decay resistance. Within a species, outer bark contained the greatest quantities of extractable total phenols followed by inner bark, heart wood, and sapwood. Outer barks also had the highest extractable tannin concentrations. Woody tissues contained very low concentrations of tannin compared with the barks. Total phenol concentrations were highest in the heart wood of red cedar, the most resistant, and lowest in the heart wood of silver fir, the least resistant. There was no obvious relationship between tannins, in any tissues, and the resistance gradient. Density measurements indicated minimal decay in all tissues after 1 year. At 2 years, the inner barks of Douglas-fir, western hemlock, and silver fir had decreased significantly. In general, tissues with the highest extractable phenols appear to be decomposing most slowly.

The concentration of essential oils in big sagebrush foliage, Artemisia tridentata subsp. tridentata, subsp. vaseyana and subsp. wyomingensis collected from Oregon, differed significantly between individual shrubs with no correlation to geographic site, subspecies genotype, or plant age. Essential oil composition, measured by headspace analysis, was not affected by plant age, location of tissue within the crown, or geographic site. Six of 16 compounds differed quantitatively by subspecies, with wyomingensis and tridentata having nearly the same composition. Vaseyana could be recognized by its significantly lower concentration of acetone and methacrolein, two highly volatile, non-terpenoid, constituents. The implication of these results and those of recent studies are discussed in relation to herbivory.

The sesquiterpene lactones and chromosome numbers for three chemical races of Artemisia tridentata ssp. vaseyana have been examined from four populations in western Montana. TLC analysis of the sesquiterpene lactones in the seeds and seed producing parents demonstrated that genetic exchange does occur between sympatric sesquiterpene lactone chemical races. However, other evidence suggests that introgression between these races is restricted to zones of sympatry. There appears to be no correlation between chromosome numbers and sesquiterpene lactone races.

Glandular trichomes on the epidermal surfaces of Centaurea maculosa contain the sesquiterpene lactone cnicin. The highest concentrations occurred in leaf tissues, with low quantities in the inflorescence branches, stems and heads. There was no cnicin in the roots. Concentrations in the rosette leaves ranged from about 0.5% dry weight in the spring, up to 1.0% after flowering in late summer. Leaves attached to the stems and inflorescence branches had the highest quantities of cnicin and exhibited greatest interplant variation. Their summer levels were close to 2% with peak concentrations in October after the tissue was dead and dehydrated. Cnicin was detected only at trace levels in the soils at the study site. The allelopathic potential of cnicin is discussed.

Flaming combustion is dependent upon the production of flammable volatiles that originate from the heating of the fuel materials. The thermal reactions that take place during this heating are determined by the chemical composition of the fuel. A knowledge of fuel chemistry and thermal reactivity can be useful in understanding and predicting fire behavior. Four plant materials were studied because their thermal decomposition curves showed unusually strong peaks from unknown combustible volatiles. The objective was to isolate and identify the chemical source of these volatiles. The tissues were methodically fractionated by following previously published techniques. Effects of each fractionation were carefully monitored by thermogravimetric analysis before and after treatment. Arabinogalactan was identified as the source of 325–350 °C volatiles from western larch (Larixoccidentalis Nutt.) wood. The major component of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) bark that decomposed above 400 °C was suberin. Foliage from gallberry (Ilexglabra (L.) Gray) and ponderosa pine (Pinusponderosa Laws.) contained cutin, which was responsible for their volatiles produced above 400 °C. The thermal behaviors of suberin and cutin reflect their similar chemical composition. The presence of these chemical components may produce similar thermal behavior in numerous other plant tissues.

It has been shown that simultaneous attrition of cellulose in an attritor containing stainlesssteel beads results in a substantial enhancement of the enzymatic hydrolysis. The attrition exerts two opposing effects, continuous delamination and comminution of the substrate with formation of new reactive sites and a gradual denaturation and inactivation of the enzyme. Consequently, the hydrolysis proceeds very rapidly at first and levels off at about 70% saccharification of the substrate. Accumulation of hydrolysis products is also responsible for inhibition of the enzyme. The attrition method is effective for the saccharification of cottonwood in which the cellulosic microfibrils are embedded in a matrix of lignin and hemicelluloses. A comparison between the saccharification of wood, lignocellulose, holocellulose, and cellulose with simultaneous attrition showed that the lignin component provided more hindrance toward the saccharification process than hemicelluloses, which are themselves subject to enzymatic hydrolysis.

Pyrolysis—mass spectrometry in combination with discriminant analysis and a newly development non-supervised mixture analysis approach is shown to provide valuable information about the biochemical composition of wood and wood products. The application of this technique to the chemotaxonomy of sagebrush (Artemisia) species as well as to the quality control of wood pulping processes is discussed. With regard to the latter application strong correlations are found between classical lignin and xylan determinations and direct pyrolysis—mass spectrometric analysis results.

The leaves of Artemisia nova Nelson are covered with a dense layer of nonglandular trichomes that obstruct the observation of glandular trichomes on the leaf surfaces. An acid-staining technique was developed that eliminates interference from the nonglandular trichomes and stains the glandular ones red, allowing them to be seen under a light microscope. Using this method it was found that these glands develop on both leaf surfaces, except over veins, and cover 21–35% of the leaf surface area at densities of 50–70 per mm 2 . Mature glands are sac-like structure with a thin sheath or cuticle surrounding a clear transparent fluid. This fluid contains all of the sesquiterpene lactones present in the leaves, and some of the monoterpenes. These terpenoids were responsible for the red color of the glands after acid treatment.

The leaves, litter, and soil from within a community of Artemisia tridentata ssp. vaseyana were analyzed for secondary metabolic products. Methacrolein, five monterpenes, three sesquiterpene lactones, six coumarins, and one flavonoid were identified in the leaves; the contents of the litter were nearly identical. Soils collected directly beneath the shrubs contained the three sesquiterpene lactones, two coumarins and an unknown flavonoid. The litter and water extracts of the litter inhibited the germination of sagebrush seeds. Soils charged with monoterpenes from sagebrush leaves also inhibited seed germination. In addition, the monoterpene contents from eight sagebrush taxa collected from Western Montana are reported.

It has been shown that the rate of enzymatic saccharification of cellulosic materials including pure cellulose, newsprint, lignocellulose and wood can be substantially increased by simultaneous wet milling. The cellulosic substrates were wet milled with a variety of grinding elements, such as sand, glass beads, and stainless-steel beads, agitated in a shaker bath. Simultaneous hydrolysis was achieved with a 2% substrate slurry in a 0.1M acetate buffer at 45/sup 0/C and pH 5. The effectiveness of this process was dependent upon the lignified matrix of the cellulose microfibrils, the grinding elements, and the oscillation frequency of the shaker bath. Wet milling pure cellulose for 48 h, with 3.5 mm glass beads and 200 oscilations/min (opm), yielded 1031 mg reducing sugar/g substrate (93% saccharification) as compared to 483 mg (44%) for the ball-milled sample and 253 mg (23%) for the unmilled material. With the lignified substrates, stainless-steel beads (3.5 mm) were more effective than glass. For lignocellulose 529 mg sugar/g substrate (93% saccharification) could be obtained by wet milling with cellulase for 24 h. This was about three times greater than that of the ball milled and 10 times greater than that of the unmilled substrates. The method was also effectivemore » for wood particles (60 mesh) giving 143 mg sugar/g wood (approx. 38% saccharification) in 48 h, whereas the ball-milled sample gave only 79 mg (21%) and the unmilled substrate 38 mg (10%). These observations can be explained on the basis of the current crystalline theory for the morphology of the cellulosic microfibrils. The advantage of wet milling and simultaneous hydrolysis apparently depends on a continuous generation of accessible sites and a sustained rapid hydrolysis rate as the saccharification proceeds, where in the pretreated substrates the hydrolysis rate slows down as the active sites are reduced.« less

Samples of Artemisia tridentata spp. vaseyana, tridentata and wyomingensis were collected from various locations throughout the state of Montana and the sesquiterpene lactone content of their leaves were analyzed by TLC. The major lactones present in each subspecies (I–VI) were isolated and chemically identified. The results showed a definite chromatographic pattern and a high degree of uniformity for each subspecies within the state of Montana. However, the comparison of these data with the analysis of a few samples obtained from the state of Wyoming failed to substantiate the general applicability of the above pattern to other ecosystems and the correlation of the chemotaxonomy with morphological identification of the plants involved.

Samples of Artemisia arbuscula ssp. arbuscula , A. tridentata ssp. tridentata , ssp. wyomingensis , ssp. vaseyana and ssp. vaseyana f. spiciformis were collected from various locations in Montana and analyzed by TLC for their sesquiterpene lactone content. Artemisia tridentata ssp. tridentata and ssp. wyomingensis are distinct morphologically and chemically, whereas ssp. vaseyana has three distinct chemical groups not yet separated morphologically. Artemisia arbuscula ssp. arbuscula and A. tridentata ssp. vaseyana f. spiciformis are easily separated by morphology but have identical TLC patterns. It has been further shown that the sesquiterpene lactones produced for a particular species or subspecies are the same regardless of the time of the year collected, although the quantity varies from winter to summer.

Water and solvent extracts from the aerial tissues ofCentaurea maculosa, spotted knapweed, inhibited the root growth of lettuce. Column chromatography and lettuce bioassay of a chloroform extract led to the isolation of cnicin, a sesquiterpene lactone. Pure cnicin was bioassayed at 0, 1, 2, 4, 6, 8, and 10 mg/5 ml water with lettuce, created wheatgrass, bluebunch wheatgrass, rough fescue, western larch, lodgepole pine, and spotted knapweed. Germination was inhibited at one or more concentrations for all species except lodgepole pine and spotted knapweed. Growth, particularly of the roots, was retarded between 1 and 4 mg of cnicin. Lettuce, bluebunch wheatgrass, and spotted knapweed were inhibited significantly at all concentrations tested.

Samples of current year's growth of leaves and stems were collected in February 1983 from basin big sagebrush (Artemisia tridentata Nutt. tridentata), Wyoming big sagebrush (A.t. wyomingensis Beetle and Young), mountain big sagebrush (A.t. vaseyana [Rydb.] Beetle), and black sagebrush (A. nova Nels.) on a mule deer (Odocoikus hemionus hemionus) winter range near Gardiner, Montana. Samples were from both lightly and heavily used plants (form classes) within each taxon. Crude terpenoids were separated into 3 groups: headspace vapors, volatile, and nonvolatile crude terpenoids. Compounds in each group are thought to stimulate the sensory organs of mule deer. Individual compounds were identified and quantified for comparison with preference ranks among taxa and between utilization form classes. Seven compounds were selected by discriminant analysis as indicators among the 4 taxa, with methacrolein+ethanol, p-cymene, and the sesquiterpene lactones the most probable preference determinants. Seven other compounds were found useful for separating plants within taxa into form classes. Chemical differences between the 2 form classes, however, were less distinguishable than were those among the 4

Five foliar constituents were measured seasonally from the three subspecies of big sagebrush in Montana. Monoterpene, crude terpenoid, and crude fat levels were lowest in the spring, increased through the summer with maximum quantities at flowering or in the fall and winter months thereafter. Crude protein and total nonstructural carbohydrates were at highest concentrations in the spring, decreased in the summer, and rose again in the fall. Sagebrush foliage consists of an extemal and internal component. The external material is glandular secondary metabolic products, primarily terpenoids, and cuticular waxes. The internal constituents are cell-wall polymers, protein, nonstructural carbohydrates, and lipids. A 5-minute chloroform extraction of fresh whole leaves removed the external material (crude terpenoids) with minimal affect on the internal components. Steam distillation extracted the epidermal terpenoids and the internal nonstructural carbohydrates leaving the cuticular waxes and protein in the dry matter residue. Plants are capable of biosynthesizing a tremendous number of chemicals that have potential uses as food, fiber, fuels, and chemicals (Buchanan et al. 1978 a,b). Many of these resources, however, have been unutilized because of high costs, inadequate technology and limited knowledge of chemical composition. The rising cost of fossil fuels, particularly oil, has stimulated an interest in the chemicals and biomaterials that can be derived from plants. In the United States and Mexico research is being directed toward both native and introduced species that have evolved and adapted to the harsh semiarid and arid environments (Campos-Lopez and RomanAlemany 1980, Johnson and Hinman 1980), where inadequate water supplies have limited agricultural development. On these drier sites, new crops could be established without affecting current food and fiber production. Big sagebrush (Artemisia tridentata) is an abundant shrub on semiarid rangelands with considerable economic and biological impact (Gifford et al. 1979). Its distribution and population densities have increased during the last century due to overgrazing of the associated grasses, fire control, and the shrubs' inherent resistance to herbivores (Morris et al. 1976, Young etal. 1979). Improvement of sagebrush-grasslands for livestock production is a desirable management practice and requires the eradication of sagebrush. This can be accomplished by a variety of techniques with variable costs and returns (Nielsen 1979). Harvesting the shrubs for their biomaterials might be a feasible alternative to destroying them and could provide some management flexibility for sagebrush

The sesquiterpene lsctones of sagebrush occur in glandular trichomes on the leaf surface and can be extracted in 1 to 2 minutes with chloroform. Analysis of this extract by thin-layer chromatography can be used as a taxonomic characteristic. The analysis of sesquiterpene lactones by thin-layer chromatography (Kelsey et al. 1976) can be used as a taxonomic character along with morphology and ecology to help identify or separate species and subspecies of sagebrush (Artemisia, section Tridentatae). Recently it was discovered that these compounds are located in glandular trichomes on the leaf surfaces and can be easily and rapidly isolated with a chloroform wash (Kelsey and Shafizadeh 1980) eliminating the need for the extensive extraction procedures reported previously (Kelsey et al. 1976). Methods Ten to twenty sagebrush leaves from a fresh or air-dried sample were placed into a test tube, covered with one milliliter of chloroform, and shaken for I to 2 minutes. The leaves were removed, discarded, and the chloroform evaporated from the extract. Evaporation was accelerated by blowing a stream of air over thechloro

Highlight: The aerial parts of sagebrush contain many interesting natural products. The sesquiterpene lactones are a class of compounds that can be easily extracted from these plants and then analyzed by thin-layer chromatography. When used in combination with the morphological characteristics, the sesquiterpene lactones can provide useful taxonomic markers that aid in separating various sagebrush taxa.

Spotted knapweed (Centaurea maculosa Lam.) is a noxious plant that has invaded many native ranges and open woodlands of western Montana. Knapweed is generally considered to have a low palatability to domestic livestock and wildlife, but local ranchers have observed sheep, goats, and some cattle ingesting large quantities of fresh knapweed during the spring and knapweed silage and hay during the winter. Nutrient analysis of plants collected prior to flowering showed neutral detergent fiber at 24.2 to 53.0% (dry wt.), ether extract 3.1 to 9.0%, crude protein 6.2 to 18.2%, total nonstructural carbohydrates 11.0 to 27.5%, ash 4.9 to 9.3%, in vitro dry matter digestibility 53.2 to 61.8%, and gross energy 4,088 to 4,539 cal/g. Crude protein and nonstructural carbohydrates were most concentrated during the spring growth period when stems were developing. As the stems matured during summer they became more fibrous resulting in lower protein and carbohydrate levels. Just prior to flowering, tall plants with stems approaching 1 m had significantly higher fiber, but lower ether extract, carbohydrates, and in vitro dry matter digestibility than plants with stems less than 0.5 m. Crude protein, ash, and gross energy were the same for both groups. It was concluded that spotted knapweed does have some nutritional value as a livestock forage. Spring grazing of knapweed or harvesting for a winter forage may be useful in the control of this noxious plant.

The visibility of leaf glandular trichomes with lOx magnification was examined for 7 sagebrush taxa. In 75% of the A rtemisia nova plants the glands were easily observed protruding through a layer of nonglandular trichomes (hairs). On A. arbuscula and the 3 subspecies of A. tridentata the glands were covered by the hairs and were not visible. These structures can be observed in the field with a hand lens and provide a supportive characteristic for the identifica

The infiuence of crude terpenoid content on in vitro organic matter digestibility (IVOMD) was determined for basin big sagebrush (ArteMia trident& Nutt. ssp. tridentata), Wyoming big sagebrush (A.t. ssp. wyomingensis Beetle and Young), mountain big sagebrush (A.t. ssp. vaseyana [Rydb.] Beetle), and black sagebrush (A. nova Nels.). IVOMD was determined using mule deer (OdocoiIeus hemionus hemionus), sheep (Ovis ammon a&s), and steer (Bos taurus) rumen inocula with current year’s growth collected from the 4 taxa at a common site on 1 Jan., 15 Feb., and 1 Apr. 1981. All inocuia had similar digestive efficiency. Extracting crude terpenoids from foliage increased IVOMD by an average of 12.3% overall. Few differences in IVOMD among taxa and dates were evident in foliage after crude terpenoids had been extracted. Order of increasing digestibility among taxa without crude terpenoids extracted was black sagebrush, mountain, Wyoming, and basin big sagebrushes, respectively. IVOMD generally Increased from January to April as crude terpenoids decreased. Crude terpenoid concentrations were lowest in mountain big sagebrush, intermediate in black sagebrush and Wyoming big sagebrush, and greatest in basin big sagebrush.