Developmental Morphology of New World Podostemaceae: Marathrum and Vanroyenella

Podostemaceae live in swift-running rivers with stony beds, mainly in the Tropics. This article is a comparative study of three Marathrum spp. (M. rubrum, M. schiedeanum, and M. tenue) and the monotypic genus Vanroyenella (with V. plumosa). The study is based on material from Mexico. Marathrum rubrum and V. plumosa are Mexican species, whereas the other two species have wider ranges in Central America. Developmental features of Marathrum and Vanroyenella are described and compared with other NewWorld Podostemoideae. Green prostrate roots with asymmetric caps are fixed to the rock by adhesive hairs. Endogenous shoot buds are formed along the roots. They grow into thalloid (dorsiventrally flattened) stems that serve as holdfasts with adhesive hairs. Many compound leaves are dithecous; i.e., they have two sheaths, arranged in the same plane as the primary pinnae. These dithecous leaves can be called “mother leaves” because they give rise to daughter leaves in both their right and left sheath. One of the two sheaths of a dithecous leaf may be also occupied by a fasciculate inflorescence with one to 13 flowers that develop and open one by one. The close relationship of Marathrum and Vanroyenella (as suggested by molecular data) is corroborated by fundamental morphological similarities. One of the seemingly unique features of Vanroyenella is the feather-like construction of the leaves, with filamentous segments arising directly from the rachis. Essential features of pinnate leaf development, however, are shared with Marathrum spp

A Phytochemical Study of Selected Podostemaceae

Podostemum ceratophyllum contains γ-mangostin and its 6-glucoside. The aglycone is also present in Marathrum, Oserya, and Vanroyenella, but is absent from Tristicha. Anthocyanins were identified from all genera, but no additional fiavonoids were detected. Condensed and hydrolyzable tannins, iridoids, cyanogenic glycosides, and alkaloids were lacking in all Podostemaceae examined. Phytochemical constituents do not clarify the uncertain systematic affinity ofPodostemaceae, but emphasize the generally accepted taxonomic isolation of this family

Developmental morphology of branching flowers in Nymphaea prolifera

Nymphaea and Nuphar (Nymphaeaceae) share an extra-axillary mode of floral inception in the shoot apical meristem (SAM). Some leaf sites along the ontogenetic spiral are occupied by floral primordia lacking a subtending bract. This pattern of flower initiation in leaf sites is repeated inside branching flowers of Nymphaea prolifera (Central and South America). Instead of fertile flowers this species usually produces sterile tuberiferous flowers that act as vegetative propagules. N. prolifera changes the meristem identity from reproductive to vegetative or vice versa repeatedly. Each branching flower first produces some perianth-like leaves, then it switches back to the vegetative meristem identity of the SAM with the formation of foliage leaves and another set of branching flowers. This process is repeated up to three times giving rise to more than 100 vegetative propagules. The developmental morphology of the branching flowers of N. prolifera is described using both microtome sections and scanning electron microscop

Tres nuevos registros para México de plantas acuáticas vasculares

Bergia capensis L. (Elatinaceae), Eichhornia paniculata (Sprengel) Solms-Laub. (Pontederiaceae), and Nymphaea novogranatensis Wiersema (Nymphaeaceae), three species of aquatic vascular plants, are reported for the first time from Mexico, all of them growing in the Isthmus of Tehuantepec area, state of Oaxaca.Se registran por primera vez para México, en particular del Istmo de Tehuantepec, Oaxaca, tres especies de plantas acuáticas vasculares, a mencionar: Bergia capensis L. (Elatinaceae), Eichhornia paniculata (Sprengel) Solms-Laub. (Pontederiaceae) y Nymphaea novogranatensis Wiersema (Nymphaeaceae)

Preanthesis Cleistogamy in the Genus Podostemum (Podostemaceae)

Podostemum from South America (P. comatum, P. distichum, P. irgangii, P. muelleri, P. ovatum, P. rutifolium subsp. rutifolium, P. scaturiginum, P. weddellianum) and the North American P. ceratophyllum. Fluorescence microscopy was used to determine whether pollen tubes were present in the stigmas of unopened flowers from 109 collections. Preanthesis cleistogamy was documented in P. weddellianum, representing the second report of this phenomenon in the genus (previously documented in P. ceratophyllum). The 12 collections with preanthesis cleistogamy represent populations from throughout the geographic range of P. weddellianum. It is hypothesized that preanthesis cleistogamy evolved twice within Podostemum, once in P. ceratophyllum and once in P. weddellianum

The biology of three Mexican-American species of Triatominae (Hemiptera: Reduviidae): Triatoma recurva, Triatoma protracta and Triatoma rubida

The values of biological parameters related to hatching, lifespan, the number of blood meals between moults, mortality, time lapse before the beginning of feeding, feeding time and defecation delay for each instar of three Mexican-American species of Triatominae, Triatoma recurva, Triatoma protracta (former subspecies protracta) and Triatoma rubida (former subspecies uhleri), were evaluated and compared. No significant (p > 0.05) differences were recorded among the three species with respect to the average time required to hatch. This time was approximately 19 days. The average egg-to-adult development time was significantly (p < 0.05) shorter for T. rubida. The number of blood meals at each nymphal instar varied from one-five for each species. The mortality rates were higher for the first-instar nymphs of the three species studied. The mean time lapse before the beginning of feeding was between 0.3-3 min for most nymphs of all instars of each species studied. The mean feeding time was the longest for T. recurva, followed by T. protracta. The defecation delay was less than 10 min for T. recurva and T. rubida. Given these results, only T. rubida should be considered an important potential vector of Trypanosoma cruzi transmission to humans in areas of Mexico where these species exist, whereas T. recurva and T. protracta would be of secondary importance