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

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

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

Development and Vasculature of the Flowers of \u3ci\u3eLophotocarpus calycinus\u3c/i\u3e and \u3ci\u3eSagittaria latifolia\u3c/i\u3e (Alismaceae)

The development of the bisexual flower of Lophotocarpus calycinus and of the unisexual flowers of Sagittaria latifolia has been observed. In all cases floral organs arise in acropetal succession. In L. calycinus, after initiation of the perianth, the first whorl of stamens to form consists of six stamens and is ordinarily followed by two alternating whorls of six stamens each. The very numerous carpels are initiated spirally. In the male flower of S. latifolia the androecium develops in spiral order. A few rudimentary carpels appear near the floral apex after initiation of the stamens. There are no staminodia. The female flower has a similar developmental pattern to that of Lophotocarpus except that a prominent residual floral apex is left bare of carpels. The vascular system in all flowers is semiopen, with vascular bundles passing to the floral organs in a pattern unrelated to the relative positions of those organs. The androecia of these two taxa are similar to those of some Butomaceae and relationships based on ontogeny and morphology are suggested. The gynoecia are meristically less specialized but morphologically more specialized than the gynoecia of Butomaceae

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

Floral Development and Vasculature in \u3ci\u3eHydrocleis nymphoides\u3c/i\u3e (Butomaceae)

The flower of Hydrocleis nymphoides consists of three sepals which arise in spiral succession, three simultaneously arising petals, numerous stamens and staminodia which arise in centrifugal order, and six carpels. A residual apex remains at maturity. The first-formed members of the androecium are stamens and the later-formed members are staminodia which develop below the stamens and which become outwardly displaced during expansion of the receptacle. The androecium is supplied by branching vascular trunk bundles. The carpels are completely open but the ventral margins are slightly conduplicately appressed basally. A single dorsal bundle provides the stigmatic area with vascular tissue, and a network of small placental bundles supplies the numerous laminar ovules. There are no clearly defined ventral bundles. It is suggested that Hydrocleis nymphoides is neither the most primitive nor the most advanced member of the family. A pattern of phylogenetic reduction in the androecium and receptacle is suggested for the entire family