Identifying pollen grains of Typha latifolia, Typha angustifolia, and Typha ×glauca

Typha angustifolia L. and Typha ×glauca Godron have increased their ranges on the North American continent over the past 150 years, and the pollen record has potential to document this spread. In T. angustifolia, pollen disperses as a reticulate, monoporate monad, similar in appearance to the pollen of Sparganium eurycarpum Engelm. Typha angustifolia and Sparganium are generally not distinguished, and T. ×glauca is rarely shown on pollen diagrams. My study of pollen reference material shows that Typha monads and Sparganium can be separated using diameter and roundness at a known level of statistical confidence. Typha monads are on average significantly smaller in diameter (mean and standard deviation = 22.7 ± 2.6 µm) than Sparganium (25.3 ± 2.7 µm). The incidence of angularity is higher in T. angusti folia pollen grains, whereas Sparganium grains are more often rounded. The pollen signature of T. ×glauca consists of mostly monads, but can contain up to 30% dyads, and (or) 14% tetrads, and (or) 10% triads. I suggest that T. angusti folia and T. ×glauca can be identified as one category in the pollen record and, where their dates of arrival are known, this category may be used as a chronostratigraphic indicator.Key words: Typha, Sparganium, pollen, invasive species, wetlands.

Characterization of Root-Associated Methanotrophs from Three Freshwater Macrophytes: Pontederia cordata, Sparganium eurycarpum, and Sagittaria latifolia

ABSTRACT Root-associated methanotrophic bacteria were enriched from three common aquatic macrophytes: Pontederia cordata,Sparganium eurycarpum, and Sagittaria latifolia. At least seven distinct taxa belonging to groups I and II were identified and presumptively assigned to the generaMethylosinus, Methylocystis,Methylomonas, and Methylococcus. Four of these strains appeared to be novel on the basis of partial 16S ribosomal DNA sequence analysis. The root-methanotroph association did not appear to be highly specific, since multiple methanotrophs were isolated from each of the three plant species. Group II methanotrophs were isolated most frequently; though less common, group I isolates accounted for three of the seven distinct methanotrophs. ApparentKm values for methane uptake by representative cultures ranged from 3 to >17 μM; for five of the eight cultures examined, apparent Km values agreed well with apparent Km estimates for plant roots, suggesting that these strains may be representative of those active in situ.

Demographics of Lestes disjunctus disjunctus (Odonata: Zygoptera) in a riverine wetland

I investigated the demographics of Lestes disjunctus disjunctus inhabiting a riverine wetland adjacent to the St. Marys River, Michigan. The areal extent of cover types within the 4.03-ha study area was measured and the densities of all life stages of L. d. disjunctus in separate cover types were converted to population estimates. Data were then analyzed using life-table techniques. The 1982 cohort oviposited an estimated 944 300 eggs in the 4.03-ha study area. Mortality in the egg stage was estimated to be 22.6%, of which 6.0% was associated with hatching and 16.6% was attributed to habitat loss. Survival through all larval instars was 5.5%. Mean larval production was 135 mg dry mass∙m−2∙year−1. The mortality rate was greatest in final-instar larvae. Instars F-8 through F-6 dispersed from wracks to Sparganium eurycarpum beds. The female:male ratio of instars F-2 through F was 1.08:1.00 and varied from 1.91:1.00 to 1.01:1.00 in the adult stage. An estimated 20 100 adult females emerged from the 4.03-ha study area, yielding a survival rate from the egg to adult stage of 4.3%. Lower potential fecundity in 1983 (45.2 eggs/female) than in 1982 (73.5 eggs/female), combined with low survival, yielded a net reproductive rate (R0) of 0.97 and a population rate of increase (r) of −0.03.

Growth and Development of Giant Burreed (Sparganium eurycarpum)

Outdoor experiments were conducted at two locations in Minnesota to characterize the growth, development, and vegetative reproduction potential of giant burreed grown with and without wild rice. Giant burreed growth was influenced by environment more than the presence of wild rice. Shoots emerged from corms 2 to 3 wk after planting (WAP), and continued throughout the growing season. Giant burreed attained a maximum height of 135 cm with an average 36 shoots/plant. Rhizome production started 4 to 6 WAP, and continued throughout the growing season. Corm formation at the base of shoots started 8 WAP and continued throughout the growing season. Rhizomes grew to a maximum cumulative length of 2500 cm/plant spreading in all directions and produced up to 250 buds/plant. Corm and rhizome bud viability was 15 and 10%, respectively. These data suggest that giant burreed grown in wild rice should be controlled by 2 to 3 wk after emergence to prevent vegetative reproduction.

Effects of Glyphosate and Surfactant Concentrations on Giant Burreed (Sparganium eurycarpum) Control with a Ropewick Applicator

Field and laboratory experiments were conducted to evaluate the effect of glyphosate concentration, surfactant concentration, and ammonium sulfate on the control of giant burreed when applied through a ropewick applicator. Under non-flooded conditions, a 30% (v/v) solution of glyphosate applied with a ropewick applicator gave the highest giant burreed injury in 1987 and 1988, and reduced corm and rhizome viability compared to the nontreated control in 1987. Warm, dry conditions may have been responsible for poor long-term control in 1988 by reducing translocation of glyphosate to rhizomes. Addition of ammonium sulfate or surfactant did not influence glyphosate toxicity to giant burreed when applied with a ropewick applicator. In the laboratory, leaf necrosis at the point of application was observed with surfactant at 0.6% or 1.2% regardless of glyphosate concentration. Absorption of14C-glyphosate increased two-fold with the addition of surfactant, and translocation to roots and rhizomes decreased almost two-fold as surfactant concentration was increased from 0 to 1.2%. Electrolyte leakage increased with 30% glyphosate when surfactant concentration was increased from 0 to 1.2%. Localized leaf necrosis and disruption of tissues inside the leaf may be responsible for reduced giant burreed control with glyphosate and surfactant applied in high concentrations.

Chemical Control of Giant Burreed (Sparganium eurycarpum) in Wild Rice (Zizania palustris)

The response of giant burreed to bentazon, propanil, 2,4-D (amine salt), and 2,4-D plus crop oil (0.5% v/v) was evaluated at the 2-aerial-leaf stage of wild rice. Bentazon, 2,4-D, and 2,4-D plus crop oil at 1.1 kg/ha or more in 1984, and propanil and 2,4-D plus crop oil at 4.5 kg/ha in 1985 reduced giant burreed dry weight. Generally, herbicide rates above 1.1 kg/ha injured wild rice and reduced yields compared to weed-free controls. None of the study treatments resulted in effective giant burreed control without unacceptable injury to wild rice.