Review of \u3ci\u3eDie Infloreszenzen: Typologie und Stellung im Aufbau des Vegetationskorpers\u3c/i\u3e. Zweiter Band. 1 Teil, by Wilhelm Troll. Gustav Fischer, Jena, 1969

Review of Die Infloreszenzen: Typologie und Stellung im Aufbau des Vegetationskorpers. Zweiter Band. 1 Teil, by Wilhelm Troll. Gustav Fischer, Jena, 1969

Review of \u3ci\u3eDie Infloreszenzen: Typologie und Stellung im Aufbau des Vegetationskorpers\u3c/i\u3e. Zweiter Band. 1 Teil, by Wilhelm Troll. Gustav Fischer, Jena, 1969

Review of Die Infloreszenzen: Typologie und Stellung im Aufbau des Vegetationskorpers. Zweiter Band. 1 Teil, by Wilhelm Troll. Gustav Fischer, Jena, 1969

Anatomical Observations on Floating Leaves

An examination of 24 genera of aquatic plants having floating leaves and leaf-like thalli has been made. Functional stomata occur on the adaxial sides of floating leaves of angiosperms and some ferns, and in some floating leaves there are stomata on the abaxial surface as well. Most floating leaves have prominently chambered mesophyll, and in some instances the chambers are locally enlarged and form buoys

The Status of \u3ci\u3eErythronium albidum\u3c/i\u3e and \u3ci\u3eE. mesochoreum\u3c/i\u3e (Liliaceae) in Nebraska

Two species of Erythronium grow in the eastern quarter of Nebraska, but there are none elsewhere in the State. Erythronium albidum is locally abundant, mostly in upland bur oak forests, and has been collected in 18 counties since 1864. Erythronium mesochoreum is becoming rare because its habitat--virgin tall-grass prairie--is disappearing. It is known to grow now in six east-central counties, but it probably could be found in some remnant prairies in all counties south and east of the Platte and Big Blue rivers, respectively. Distributional data about these species is herein brought up to date relative to earlier published reports. Although the literature suggests that the two species are not always clearly distinct, observations of living specimens in Nebraska mostly support their status as separate species

Anatomical Observations on Floating Leaves

An examination of 24 genera of aquatic plants having floating leaves and leaf-like thalli has been made. Functional stomata occur on the adaxial sides of floating leaves of angiosperms and some ferns, and in some floating leaves there are stomata on the abaxial surface as well. Most floating leaves have prominently chambered mesophyll, and in some instances the chambers are locally enlarged and form buoys

Reproductive Structure and Organogenesis in a Cottonwood, \u3ci\u3ePopulus deltoides\u3c/i\u3e (Salicaceae)

The organogenesis of inflorescences, flowers, and fruits was followed for two years in a male and a female tree of eastern cottonwood, Populus deltoides. Soon after anthesis, an inflorescence for the next year is initiated as a continuation of the apical meristem in most axillary buds of the extension shoot of the current year. Bract and then floral primordia arise helically, and by the end of summer all floral appendages are evident. Individual perianth parts are evident early in ontogeny but not at anthesis; they are vascularized independently by distal traces of discrete vascular strands that also serve the androecium or gynoecium. The stamens arise and are vascularized in centrifugal order, the first- and last-formed stamens receiving their traces from the proximal and subdistal divisions, respectively, of the discrete vascular strands serving groups of stamens. There is no external evidence of stamen fascicles. Centrifugal polyandry is interpreted as a derived state in Populus. The usual number of carpels in P. deltoides is three, but two and four are not rare, and two is probably the plesiomorphic state for the genus

Floral Morphology and Phylogeny in the Hydrocharitaceae

The vascular anatomy of 13 of the 15 genera of the Hydrocharitaceae has been studied, and certain aspects of floral morphology are considered. The flowers of the family show a broad range of specialized structures combined with primitive characteristics. The origin of paired and single stamens is interpreted as probable modifications of fascicled stamens. Extreme reduction in the androecium is shown for several genera. Tendencies toward reduction and fusion within the gynoecium are pronounced. Most genera are at least slightly syncarpous, but a few are apocarpous. The inferior ovary is appendicular in nature, with some genera exhibiting more complete fusion than others. The carpels are open and show no signs of closure. The multicarpellate genera have the most primitive gynoecia within the family while the tricarpellate genera exhibit the most advanced types in the family. Intermediate forms are Blyxa and Vallisneria

Morphology and Development of the Flowers of \u3ci\u3eBoottia cordata\u3c/i\u3e, \u3ci\u3eOttelia alismoides\u3c/i\u3e, and Their Synthetic Hybrid (Hydrocharitaceae)

The inferior ovary of Boottia cordata, Ottelia alismoides, and their hybrid is appendicular in nature, the carpels are congenitally only slightly connate, and they are unsealed. All floral organs except the sepals originate from common primordia in the female and bisexual flowers. A flat residual floral apex is present. There is a vestigial superior ovary of three ontogeneticallv fused carpels in the male flower of Boottia cordata. The hybrid is intermediate in many characteristics and has partially fertile stamens and staminodia. The sequence of development in all flowers is acropetal. These plants appear to be related to the Butomaceae and they show evolutionary tendencies parallel to those in the Nymphaeaceae