The early development of nodal adventitious roots with root hairs and root hair deformations by Elodea nuttallii (Planchon) H. St. Johns

Elodea nuttallii is a globally distributed aquatic vascular plant that provides many ecosystem services. In the sediment its roots fulfill important geochemical functions and initiate biological interactions within the rhizosphere. However, the macro-anatomy and development of its roots remained widely uncharacterized. This study aims to analyze the early morphogenesis of Elodeas roots and their general macro-anatomy. Therefore, plants free of roots were planted on two different sediment types and harvested along an individual time axis after the first roots were developed. All plants were photographed, measured and the roots were microscopically analyzed. Elodea has nodal adventitious roots, non-woody and from shoots. All roots have a root tip with a well-developed apical meristem and a root cap, an elongation zone, and a well-developed maturation zone with root hairs. Root hair deformations like swollen root hairs, swollen root hair tips, and branched root hairs most often developed when plants were grown on nutrient-poor, coarse-grained sediment. We here present a first description of the morpho- genesis and macro-anatomy of roots developed by E. nuttallii. This work will improve our understanding of this important species and foster further studies on the coupling between physiological processes, the morphogenesis, anatomy, ecosystem services, economical use, and management strategies related to E. nuttallii.

A practical technique for preserving specimens of duckmeal, Wolffia (Araceae)

Making identifiable herbarium vouchers of the minute aquatic vascular plant duckmeal, Wolffia (Lemnoideae; Araceae) has typically required plants to be preserved in transparent, space-consuming vials that are fragile, difficult to work with, and labourious to prepare. An alternative technique for dry-mounting Wolffia within a layer of transparent, acid-free glue presents a promising alternative. Although the largely water-filled individual plants still compress substantially, this preparation technique results in specimens that retain their colour, size, and, most important, their shape. This greatly enhances the possibility of confident identification and simplifies both specimen preparation and storage.

Occurrence, Composition and Formation of Ruppia, Widgeon Grass, balls in Saskatchewan Lakes

Widgeon Grass (Ruppia maritima) is an aquatic vascular plant (Ruppiaceae) which has been the source for rare balls of plant material found at the shores of lakes on four continents. In North America, the lakes involved were in North Dakota, Oregon, and now northern and southern Saskatchewan. The formation of the balls has not been observed in nature, but similar balls have been produced in other studies with Posidonia or Turtle Grass (Hydrocharitaceae) fibers under the wavelike action in a washing machine. Our samples are from a saline lake in southern Saskatchewan (49°N), and an over 40-year-old sample from an unknown lake north of the boreal transition zone (52°N). Comparisons of the plant material with herbarium specimens confirm that the balls are almost entirely comprised of Ruppia maritima, with minor items including invertebrate animal parts, sand pebbles and feathers. The context in which the material was found is consistent with the proposition that they are formed by Ruppia inflorescences breaking apart, drifting to near shore due to wind and being rolled into balls by wave action.