Shoot Architecture and Branching Pattern in Perennial Hydatellaceae (Nymphaeales)

Abstract

New data are presented on shoot architecture and branching pattern in one of the two perennial species of Hydatellaceae (Nymphaeales), Trithuria filamentosa, in the first detailed comparative study that covers both development and anatomy. Perennial rhizomes of T. filamentosa bear vegetative leaves and leafless stalks of reproductive units. Rhizome growth is sympodial. Each shoot produces four to nine vegetative leaves and in its distal part one or two lateral shoots and one to three reproductive units. Lateral shoots develop in the axils of vegetative leaves. The two first leaves of each lateral shoot lie in a transversal plane, with a divergence angle close to 180°; they are interpreted as prophylls. From the third leaf onward, divergence angles are close to the Fibonacci pattern. Stalks bearing reproductive units are interpreted as the uppermost lateral extra-axillary organs that continue the shoot phyllotaxic spiral; in this interpretation, the mode of insertion of reproductive units in T. filamentosa is similar to the mode of flower insertion in Nymphaea. An alternative but less plausible interpretation assumes presence of both lateral extra-axillary and terminal reproductive units.

Floral biology and ovule and seed ontogeny of Nymphaea thermarum, a water lily at the brink of extinction with potential as a model system for basal angiosperms

“…The developmental morphology of flowers and fruits within Nymphaeales has been documented in most genera and subgenera (Chiflot, 1902;Heslop-Harrison, 1955a, b;Moseley, 1961;Khanna, 1964b;Ramji and Padmanabhan, 1965;Schneider, 1976Schneider, , 1982Schneider, , 1983Schneider and Moore, 1977;Schneider and Chaney, 1981;Moseley et al, 1984;Williamson and Moseley, 1989;Schneider et al, 2003;Endress, 2001Endress, , 2005Grob et al, 2006;Rudall et al, 2007;Zhou and Fu, 2007;Hu et al, 2009;Rudall et al, 2009;Sokoloff et al, 2009Sokoloff et al, , 2010Vialette-Guiraud et al, 2011). Features of female gametophyte development, fertilization and seed development have also been studied, but are scattered across a century of embryological literature (Cook, 1902(Cook, , 1906(Cook, , 1909Conard, 1905;Seaton, 1908;Martin, 1946;Meyer, 1960;Khanna, 1964aKhanna, , b, 1965Khanna, , 1967Valtzeva and Savich, 1965;Schneider, 1978;Schneider and Ford, 1978;Batygina et al, 1980Batygina et al, , 1982Schneider and Jeter, 1982;Winter and Sha...…”

Embryo and seedling morphology inTrithuria lanterna(Hydatellaceae, Nymphaeales): new data for infrafamilial systematics and a novel type of syncotyly

“…A: more precisely spirodistichous). All leaves are generally similar and possess a long filiform blade of anatomical structure typical of Hydatellaceae (Rudall et al ., ; Sokoloff et al ., ). The leaves (including the leaf blade that first appears in a seedling, lb0) often possess basal auricles that differentiate late in development.…”

Defining the limits of flowers: the challenge of distinguishing between the evolutionary products of simple versus compound strobili

“…Eriocaulaceae). However, Trithuria RUs could equally be interpreted as flowers, which they resemble in several respects: apart from their condensed flower-like presentation (figure 4), there are strong developmental similarities between the bract-like phyllomes of Trithuria and the perianth of other Nymphaeales ) and the arrangement of flowers/RUs on the shoot is very similar (Sokoloff et al 2009). Furthermore, the inside-out structure of the Trithuria RU can be at least partially modified in teratological forms, producing a morphology that is closer to an orthodox flower (Rudall et al 2009a,b).…”