Spicata Var Research Articles

Hypoglycemic Polysaccharides from the Tuberous Root of Liriope spicata

Previous studies showed that the water extract and crude polysaccharides from the tuberous root of Liriope spicata var. prolifera showed high hypoglycemic and hypolipidemic activities. In the present study, two new water-soluble polysaccharides, named LSP1 and LSP2, were isolated from the active crude polysaccharides by DEAE-cellulose 52 and AB-8 macroporous resin chromatography and tested for their hypoglycemic effects. On the basis of the chemical and physical data obtained, LSP1 and LSP2 are two fructans with the molecular weights 3.20 and 4.29 kDa, respectively, which both have a backbone structure of beta-(1-->2)-fructosyl residues that branches at O-6 with fructosyl residues and terminates with a glucosyl residue and a fructosyl residue. Preliminary activity tests revealed that both LSP1 and LSP2 caused a significant decrease of the fasting blood glucose (FBG) and a significant improvement on glucose tolerance in type 2 diabetic mice. These results suggest that LSP1 and LSP2 show high potential to be explored as natural oral hypoglycemic agents.

Karyotype analysis of medicinal plant Liriope spicata var. prolifera (Liliaceae)

Karyotype of Liriope spicata var. prolifera, a Chinese endemic species, was described in detail for the first time. Its proto-variety L. spicata was also investigated for comparison. The basic chromosome number of these two species was x = 18. L. spicata var. prolifera, recorded as triploid 2n = 54, consisted of 30 metacentric chromosomes and 24 submetacentric chromosomes. Only one chromosome of the 11th group had a secondary constriction with a satellite in the short arm. L. Spicata was tetraploid 2n = 72 and consisted of four sets of 6 submetacentric chromosomes and 12 metacentric chromosomes without visible satellites. This paper provides further available data on Liriope chromosomes, and also indicates that L. spicata var. prolifera and L. spicata are probably separate species.

Effects of water extract and crude polysaccharides from Liriope spicata var. prolifera on InsR/IRS-1/PI3K pathway and glucose metabolism in mice

Aim of the study The present study was designed to investigate the effects of water extract (WE) and crude polysaccharides (CPs) from the tuberous root of Liriope spicata var. prolifer on the InsR/IRS-1/PI3K pathway and glucose metabolism in type 2 diabetic mice. Materials and methods WE and CPs were administered orally at different doses (200 and 100 mg/kg body weight) to streptozotocin (STZ)-induced type 2 diabetic male BABL/c mice, respectively. After 4 weeks of administration, immunohistochemistry and western blot were applied to detect the expression levels of insulin receptor-α (InsR-α), insulin receptor substrate-1 (IRS-1) and phosphatidylinositol 3-kinase (PI3K) in renal tissues of mice. Moreover, the hepatic glycogen content, glucokinase (GK) and glucose-6-phosphatase (G6Pase) activities were measured to investigate the effect of WE and CPs on glucose metabolism. Results Compared with diabetic control, greater immunostaining for InsR-α, IRS-1 and PI3K was present in the tubulointerstitial regions of WE and CPS groups in renal tissues and the expression levels of these three signal molecules from WE and CPs groups were significantly increased; the glycogen content and GK activity from WE and CPs groups in liver were significantly increased, yet the G6Pase activity was significantly lower. Conclusions It is demonstrated that WE and CPs can ameliorate insulin signaling transduction and glucose metabolism, as a result, lessen IR and hyperglycemia eventually. So, this study has provided more powerful evidences for Liriope spicata var. prolifer to be a potential hypoglycemic agent and insulin sensitizer.

ESSENTIAL OIL COMPOSITION OF SOME WILD AND CULTIVATED MEDICINAL PLANTS

Thymbra species are abundantly found in the wild, and also Tanacetum densum (Lab.) Schultz Bip. subsp. amani Heywood is an endemic plant of the Southeastern Anatolian, Turkey. Air-dried aerial parts of the plants were submitted to hydrodistillation, for 3 hours, using a Clevenger-type apparatus. Cultivated and wild Thymbra spicata var. spicata, Thmybra sintenisii Bornm. & Aznav. and Tanacetum densum subsp. amani species were compared for their essential oil constituents using GC/MS analysis. The results showed that the major constituents of essential oil of both Thymbra species were carvacrol, γ-terpinene, p-cymene, β-caryophyllene, myrcene and α-phellandrene. Essential oil of cultivated T. spicata contained lower carvacrol percentage (67.91%) compared to the carvacrol percentage of cultivated species (72.56%). Conversely α-pinene percentage of cultivated T. sintenisii was higher compared to wild forms. P-cymene was found second major constituent in the essential oil T. sintenisii. Tanacetum oil was pale greenish and had a pleasant odour, with a yield of 0.1% (v/w) for wild form and 0.15% for cultivated form. Twenty-three components representing 84.53-93.41% of the oil were characterized, of which bisabolone oxide (25.62%), carvacrol (26.73%), isoborneol (10.07%), borneol (14.05%), β-panasinsene (8.95%), eucalyptol (10.13%) and camphor (4.71%) were the main compounds.

In vitro activity of methanol extracts of plants used as spices against Mycobacterium tuberculosis and other bacteria

Abstract This study determined the phenolic composition of two thyme species (Lamiaceae), Origanum minutiflorum O. Schwarz and P.H. Davis and Thymbra spicata L. var. spicata, and assessed their antibacterial and antimycobacterial activities. “Kekik” is a collective term used in Turkey for plants that smell like thyme. O. minutiflorum , (locally “Sutculer kekigi”, endemic) and T. spicata var. spicata (locally “Karakekik”) are widely used in Turkey and are important export commodities. The activity of the methanol extracts of these plants is given here for the first time. T. spicata var. spicata exhibited a high level of activity against Mycobacterium tuberculosis (minimum inhibitory concentration MIC 196 μg/ml), and moderate activity (MIC 640 μg/ml) against Escherichia coli , Salmonella typhimurium , Enterobacter aerogenes , and Staphylococcus epidermidis . Carvacrol, rosmarinic acid, hesperidin and naringenin were identified as the major phenolic compounds for T. spicata var. spicata. Carvacrol, rosmarinic acid, eriodictiol and luteolin were identified as the major phenolic compounds for O. minutiflorum. The effective constituents of methanol extracts of these plants are given here for the first time.

Anti-diabetic effects of water extract and crude polysaccharides from tuberous root of Liriope spicata var. prolifera in mice

Aim of the study The present study was designed to investigate the hypoglycemic and hypolipidemic effects of the water extract (WE) and crude polysaccharides (CPs) obtained from the tuberous root of Liriope spicata (Thund.) var. prolifera Y. T. Ma, which is widely used in prescriptions of traditional Chinese medicine for the treatment of diabetes mellitus. Materials and methods WE and CPs were administered orally at different doses (200 and 100 mg/kg body weight) to normal and streptozotocin (STZ)-induced type 2 diabetic male BABL/c mice, respectively. The fasting blood glucose (FBG), lipids and insulin in serum were estimated and an oral glucose tolerance test (OGTT) was performed for the evaluation of hypoglycemic and hypolipidemic effects. Results Both doses of WE and CPs did not show any appreciable effect on FBG in normal mice. However, they caused a marked decrease of FBG and a significant improvement on glucose tolerance and insulin resistance in STZ-induced type 2 diabetic mice. In addition, while lowering total cholesterol (TC), triglyceride (TG) and low-density lipoprotein (LDL) cholesterol levels, WE and CPs elevated the relative high density lipoprotein (HDL) cholesterol level (HDL/TC) in serum. Compared to WE, the hypoglycemic and hypolipidemic effects of CPs were more marked. Conclusions The results suggest that WE and CPs may have hypoglycemic and hypolipidemic potential for the type 2 diabetes and support the traditional use of the tuberous root of Liriope spicata var. prolifera as a hypoglycemic agent.

Antimicrobial activity and chemical composition of the essential oils of Thymbra spicata var. intricata.

In this study, T. spicata var. intricata, endemic to Turkey, were collected from various localities of Mugla, Turkey. The essential oils were obtained using the hydrodistillation method. The antimicrobial activities of the essential oils on micro-organisms, including multiple antibiotic resistant bacteria, were evaluated using the disc diffusion method. The chemical composition of the essential oil was determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The essential oils were effective against Gram-positive and Gram-negative bacteria, which included multiple antibiotic resistant strains. However, Pseudomonas aeruginosa ATCC 27853 and Pseudomonas fluorescens MU 87 were resistant to these oils. The essential oils were very effective against Candida albicans. The antimicrobial activity of the essential oils showed some variations depending on the localities from which they were collected. A total 24 components were identified in the essential oil. The main components were characterized as carvacrol (75.74%), γ-terpinene (9.28%), p-cymene (7.17%), myrcene (1.39%), β-caryophyllene (1.13%) and thymol (0.15%), respectively. Key words: Antimicrobial activity, chemical composition, Thymbra spicata var. intricata

Effect of Seeding Date, Seeding Rate, and Seed Treatments on Saltgrass Seed Germination and Establishment

Inland saltgrass [Distichlis spicata var. stricta (L.) Greene], native to the western United States, has potential for use as a turfgrass and a revegetation species on saline sites. This study was conducted (i) to evaluate the effect of seeding date, seeding rate, and seed treatments on saltgrass establishment; and (ii) to determine the required accumulative growing degree days (GDD) for saltgrass to establish adequate cover (≥80%) after seeding. Seeding dates were 15 May, 15 June, and 15 July in 2006. Machine scarification and stratification broke saltgrass seed dormancy equally well. Saltgrass seeded in May established adequate coverage (≥80%) in September even using the lowest seeding rate (74 kg ha−1). For plots seeded in June, only the higher seeding rates (123 and 170 kg ha−1) established adequate coverage (≥80%) by the end of growing season. For plots seeded in July, however, even the highest seeding rate failed to establish adequate coverage in September. The accumulated GDD to achieve adequate coverage was 1748, 1663, and 1435 for 74, 123, and 172 kg ha−1 seeding rates, respectively.

Chemotypic variations of the essential oils of Mentha taxa collected in the Marmara region of Turkey

The genus Mentha L. (Lamiaceae) is represented by 16 taxa in the Flora of Turkey [1,2]. Eleven taxa belonging to 8 species (including hybrids) have been investigated for essential oils. The oils obtained by hydrodistillation using a Clevenger apparatus were analysed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). In our ongoing research into compositions of Mentha taxa in Turkey, we had previously reported on the mint oils of Northern Turkey [3]. In this study over 100 oil samples of the following taxa were investigated: M. pulegium, M. aquatica, M. piperita nm. citrata, M. rotundifolia, M. x dumetorum, M. x villosa-nervata, M. spicata var. spicata, M. spicata var. tomentosa, M. longifolia subsp. longifolia, M. longifolia subsp. typhoides. Chemotypic variations are discussed based on the previous and present results.

Activity of essential oils in vapour phase against Paenibacillus larvae

Paenibacillus larvae subspecies larvae, a Gram-positive, spore-forming bacterium, is the causative agent of the American foulbrood (AFB), one of the most serious and destructive brood diseases of honeybees. AFB is a problem for beekeepers world-wide [1]. Thus, in this study we have tested eight essential oils from aromatic plants against two strains of P. larvae, one wild strain isolated from infected honeybee colony (15/08f4) and one standard strain (ATCC 9545). For the tests we have used disc volatilization method, as the application of chemicals in vapour phase in the beehives is simple and common. In addition, several products containing thymol against parasitic mite Varroa destructor are commercially available. Four essential oils were active in the range of tested concentrations (from 1 to 256 nl/ml). The most active was EO from Armoracia rusticana (MICs 16 nl/ml) followed by Thymus vulgaris (MIC 64 nl/ml), Mentha spicata var. crispa (MICs 64 and 128 nl/l against wild and standard strain, respectively) and Satureja hortensis (MICs 128 and 256 nl/ml, respectively). The results are quite promising, the toxicity of active EO against honeybees and possible organoleptic changes of bee products will be checked in the next phase.

Improving Seed Germination of Saltgrass under Saline Conditions

Saltgrass [Distichlis spicata var. stricta (Greene)] has a great potential for use as a turfgrass and as a revegetation species of saline sites. Experiments were conducted to test the effect of the application of different concentrations of ethephon, fusicoccin, kinetin, thiourea, and Proxy on saltgrass seed germination under three salinity levels. Saltgrass germination percentage was 56% under nonsaline condition, which was reduced to 46 and 26% at 15 and 30 dS m−1 salinity levels, respectively. Ethephon application (5 mM) increased saltgrass germination percentage under the highest salinity treatment (30 dS m−1) only. However, Proxy (at 5 mM a.i.) increased saltgrass germination under all salinity treatments, reaching 97, 76, and 40% under control, 15 dS m−1, and 30 dS m−1 salinity levels, respectively. Kinetin at 0.5 to 1.0 mM did not increase saltgrass germination under nonsaline conditions but increased germination percentage by 35% at 15 dS m−1 and by 89% at 30 dS m−1 salinity. Fusicoccin (at 10 μM) and thiourea (at 30.0 mM) also increased germination percentage under all salinity treatments. Our investigation showed that 5.0 mM ethephon, 10 μM fusicoccin, 0.5 to 1.0 mM kinetin, 30 mM thiourea, and Proxy (at 5 mM a.i.) increased saltgrass seed germination under saline conditions. Proxy was the most effective in improving saltgrass germination percentage under saline conditions, followed by thiourea, fusicoccin, ethephon, and kinetin.

Relative Salinity Tolerance of Turf-type Saltgrass Selections

Salt-tolerant turfgrass is highly desirable in areas associated with saline soils or saline irrigation waters. To determine the salt tolerance of 14 saltgrass [Distichlis spicata var. stricta (Greene)] selections, two greenhouse studies were conducted by means of a hydroponic culture system. Five salinity levels (from 2 to 48 dS·m−1) were created with ocean salts. In general, turf quality decreased and leaf firing increased as salinity increased. However, varying levels of salt tolerance were observed among selections based on leaf firing, turf quality, root growth, and clipping yield. Selections COAZ-01, COAZ-18, CO-01, and COAZ-19 exhibited the best turf quality and the least leaf firing at 36 and 48 dS·m−1 salinity levels in both Experiments 1 and 2. At the highest salinity level (48 dS·m−1), COAZ-18 and COAZ-19 exhibited the highest root activity among all accessions. Salinity levels that caused 25% clipping reduction ranged from 21.2 to 29.9 dS·m−1 and were not significantly different among entries. The data on 25% clipping reduction salinity of saltgrass generated in this study rank saltgrass as one of the most salt-tolerant species that can be used as turf.

Techniques for Enhancing Saltgrass Seed Germination and Establishment

Because of its exceptional salinity tolerance, inland saltgrass [Distichlis spicata var. stricta (L.) Greene] has great potential for use as a turfgrass and revegetation species of saline sites. However, saltgrass seeds have a low germination rate due to seed dormancy. Three experiments were conducted to evaluate different seed treatments to enhance germination and establishment of inland saltgrass. In Experiment I, seven different seed treatments were tested for their ability to enhance germination percentage in the growth chamber and compared with a control of no treatment. These treatments included treatments with hot water, hydrogen peroxide (H2O2), sulfuric acid (H2SO4), potassium nitrate (KNO3), bleach, machine scarification, stratification, and hand nicking. Results indicated that germination percentage was increased only by stratification, hand nicking, and machine scarification treatments as compared with the control. In Experiment II, machine scarification, stratification, hand nicking, and the control were tested in the growth chamber. Hand nicking, scarification, and stratification increased percentage germination from 13.0% to 54.0 to 61.7%. Stratification resulted in the fastest germination, followed by hand nicking and scarification. Experiment III was conducted in the field, and seed treatments included machine scarification, stratification, and the control. Two months after seeding, plots seeded with stratified and scarified saltgrass seeds established adequate plot coverage as a turf, whereas the coverage for the control was inadequate, exhibiting inferior turf quality. In summary, stratification and machine scarification improve germination and establishment of seeded saltgrass.

Biology and Conservation of the Endangered Carson Wandering Skipper (Pseudocopaeodes eunus obscurus Austin and Emmel) in Western Great Basin Saltgrass Communities

Abstract The endangered Carson wandering skipper (Pseudocopaeodes eunus obscurus [Austin and Emmel]) survives as a relict species in four major pluvial basins in the western Great Basin of Nevada and California. This Hesperiinae is distinct from other subspecies in the genus, likely resulting from a vicariance event during the Holocene. Surviving in disjunct refugia, this butterfly has highly specialized habitat requirements and feeds only on saltgrass (Distichlis spicata var. stricta [Greene] Thorne) as larvae. Conservation of habitat patches has been highly successful. However, land development and groundwater withdrawal are in high demand surrounding the species' habitat and pose significant impacts on its survival. The species survival or extinction will be dictated by these land uses. Land development may decrease dispersal capabilities, and groundwater withdrawal may cause a vegetation shift resulting in the loss of skipper populations. Recovery will depend on the adaptive management of land uses th...

Antihypercholesterolaemic and antioxidant activity assessment of some plants used as remedy in Turkish folk medicine

Ethanolic and aqueous extracts from five plant species used in Turkish traditional medicine were evaluated for in vivo hypercholesterolaemic and antioxidant activities: Agrostemma githago L., Potentilla reptans L., Thymbra spicata var. spicata L., Urtica dioica L. and Viscum album var. album L. We assayed the effects of the administration of plant extracts on serum total cholesterol, triglyceride, HDL-C, LDL-C, glucose, AST and ALT concentrations in mice fed with cholesterol-rich diet. In addition, plasma TAA, MDA and NO x levels in the same animals were assayed. All the aqueous plant extracts did not affect the serum cholesterol concentration. However, the ethanolic extracts of Agrostemma githago, Thymbra spicata and Viscum album decreased the serum cholesterol concentration in the mice fed with high-cholesterol diet without inducing any gastric damage. The ethanolic extracts of Thymbra spicata, Viscum album, Potentilla reptans and Urtica dioica and the aqueous extract of Agrostemma githago increased the serum HDL concentration, whereas the ethanolic extracts of Agrostemma githago, Thymbra spicata, Viscum album and Urtica dioica decreased the serum LDL-C concentration. Thymbra spicata and Viscum album were observed to decrease the serum triglyceride concentration. Among the plant extracts studied, the ethanolic extracts of Thymbra spicata significantly decreased the MDA level in mice. The ethanolic extract of Potentilla reptans increased in NO x . None of these plants showed statistically prominent activity on plasma TAA. Results of the present study indicated that the ethanolic extracts of Agrostemma githago, Thymbra spicata and Viscum album showed potent hypocholesterolaemic activity in the mice fed with a diet containing high-cholesterol.

Determination of yield and yield components in wild thyme (Thymbra spicata L. var. spicata) as influenced by development stages

Thymbra spicata var. spicata, which grows wildly in the flora of Turkey, is known as thyme. A field trial was conducted to determine suitable harvesting time and cutting height for Thymbra, therefore plants in the trial were harvested at two cutting heights in various stages of development in the course of the growing season (pre-flowering, full-flowering and post-flowering). It was determined that the time of harvesting had a significant effect on herbage yields, oil percentage and oil yield. The highest drug leaf yield (3.107 t/ha) was obtained in the full-flowering stage with 10 cm cutting length, essential oil percentage ranged from 1.58 to 2.33%, the highest essential oil yield (70.7 l/ha) was obtained at the full-flowering stage with 10 cm cutting length. As a result of this study, harvesting in the full-flowering stage with 10 cm cutting height was the best treatment in respect of the yield of dry matter and oil for thyme (Thymbra spicata) cultivation.  

First Report of Brown Stripe of Saltgrass Caused by Bipolaris heveae in Colorado.

Inland saltgrass (Distichlis spicata var. stricta (L.) Greene) is indigenous to western North America and Australia and is a dioecious, rhizomatous, perennial, warm-season grass. It is commonly found in areas where salinity, alkalinity, and drought have eliminated many other types of vegetation (1). It has potential for revegetation of mine spoils or use along roadsides (2). During September 2004, multiple lenticular, brown lesions were observed on leaves of saltgrass accession no. 1023 at the Horticulture Field Research Center, Colorado State University, Fort Collins. Segments of symptomatic leaf tissue were surface sterilized in 0.5% sodium hypochlorite and placed on one-quarter-strength potato dextrose agar and incubated at 25°C in the dark. Dark green fungal colonies with aerial mycelium consistently grew on the medium. Slightly curved, ellipsoidal, pale-to-golden brown, smooth conidia 46 to 80 μm long and 13 to 17 μm wide (average 64.5 × 14.7 μm) with 6 to 9 septations formed after 7 days in cultures grown on V8 juice agar. The morphology and bipolar germination of conidia was consistent with the genus Bipolaris, however, conidia were often shorter than previously reported (3). The rDNA internal transcribed spacer (ITS) regions of one isolate were amplified using polymerase chain reaction (PCR) with universal fungal rDNA primers ITS1 and ITS4. PCR products were sequenced (555 bp) and exhibited 99% nucleotide identity to Bipolaris heveae isolates collected from zoysiagrass and bermudagrass in Japan (3) and rubber in Nigeria (4). To confirm pathogenicity, a suspension of 104 conidia per ml of water containing 0.1% Tween 20 was sprayed on saltgrass leaves to runoff. Plants were covered with transparent plastic bags and incubated at 25°C in the dark. After 72 h, the bags were removed and plants were placed in the greenhouse. Brown stripe symptoms were observed on all plants after 7 days, and B. heveae was consistently isolated from symptomatic tissue. To our knowledge, this is the first report of brown stripe on inland saltgrass caused by B. heveae.

Cold Hardiness of Saltgrass Accessions

Freezing tolerance is an environmental adaptation that significantly influences plant geographical distribution. Since differences in winter survival among saltgrass ecotypes have been observed in the field at Fort Collins, CO, the objective of this study was to determine the relative freezing tolerance, seasonal changes in the freezing tolerance, and winter survival of six accessions of saltgrass [Distichlis spicata var. stricta (L.) Greene]. Saltgrass accessions A65 and A29 were originally collected from Denver, CO, while C66 was from Humbolt Sink, NV, 32 from Wanship, UT, 55 from Hereford and 48 from Farmingdale, SD. These accessions were established in a field nursery at Fort Collins, CO. Rhizomes were sampled at monthly intervals from October 1999 through April 2000 and from October 2000 through April 2001 and subjected to laboratory freezing tests. Cold hardiness of the saltgrass accessions increased gradually during the fall with maximum hardiness occurring at midwinter. During midwinter, freezing tolerance was significantly different among accessions. Ranking of accessions for subfreezing temperature resulting in 50% mortality [LT50 (°C)] during January 2000 was A29 = 48 (−20.0) < 55 (−17.0) ≤ 32 (−15.5) ≤ A65 = C66 (−14.0). In January 2001, they were ranked with 48 = 55 (−26.0) < A65 = 32 (−23.0) < A29 (−20.0) = C66 (−18.5). In December and January sampling dates of the first season, accessions A29, 48, and 55 exhibited the highest relative regrowth when exposed to temperatures ≈ −20.0°C. In midwinter of the second season, accession 55 showed the highest regrowth after being subjected to temperatures ≈ −25.0°C. Accession C66 had the lowest regrowth potential after freezing treatments in both seasons. Winter survival in the field correlated negatively with LT50 value, with accessions 48, A29, and 55 demonstrating greater winter survival while C66 had the lowest percentage survival. The difference in freezing tolerance among accessions is in part associated with their origin‐inherited adaptation. This information is useful for defining the potential adaptation range of saltgrass and in saltgrass breeding projects to select and develop freezing tolerant saltgrass.

Divergence in mycorrhizal specialization within Hexalectris spicata (Orchidaceae), a nonphotosynthetic desert orchid

Evidence is accumulating for specialized yet evolutionarily dynamic associations between orchids and their mycorrhizal fungi. However, the frequency of tight mycorrhizal specificity and the phylogenetic scale of changes in specificity within the Orchidaceae are presently unknown. We used microscopic observations and PCR-based methods to address these questions in three taxa of nonphotosynthetic orchids within the Hexalectris spicata complex. Fungal ITS RFLP analysis and sequences of the ITS and nuclear LSU ribosomal gene fragments allowed us to identify the fungi colonizing 25 individuals and 50 roots. Thanatephorus ochraceus (Ceratobasidiaceae) was an occasional colonizer of mycorrhizal roots and nonmycorrhizal rhizomes. Members of the Sebacinaceae were the primary mycorrhizal fungi in every Hexalectris root and were phylogenetically intermixed with ectomycorrhizal taxa. These associates fell into six ITS RFLP types labeled B through G. Types B, C, D, and G were found in samples of H. spicata var. spicata, while only type E was found in H. spicata var. arizonica and only type F was found in H. revoluta. These results provide preliminary evidence for divergence in mycorrhizal specificity between these two closely related orchid taxa. We hypothesize that mycorrhizal interactions have contributed to the evolutionary diversification of the Orchidaceae.

345 Seed Germination of Inland Saltgrass

Distichlis spicata var. stricta (Torrey) Beetle is a native grass that tolerates salt, high pH, and some heavy metals. It has been proposed for use in several challenging environments, including mine spoils and salt-impacted areas of golf courses, but its widespread use has been hindered by several factors, one of which is seed dormancy. Dormancy appears to be coat-imposed and can be overcome by scarification in relatively young seed lots. Thirteen-year-old seeds germinated better without scarification. Seeds were tested at several constant and alternating temperatures. Temperatures around 30 °C seemed to give the highest percentage germination, approaching the viability that was shown by tetrazolium chloride tests for each seed lot. Alternating temperatures increased the germination of unscarified seeds but not as much as scarification did. Light appears to be unnecessary for germination.