Premise of research. Fossil inflorescences (scapes) producing both pedicellate flowers and sessile bulbils, both covered partially by a persistent spathe, are described from the latest early Eocene Republic flora of north-central Washington. They are associated with an individual specimen of a single bulb with attached roots, and two small flower buds that appear to represent the same plant. The morphology of these fossils closely resembles that of certain bulb-forming monocots, such as some species of the onion genus Allium and other members of Amaryllidaceae.Methodology. Compression-impression fossils preserved in a lacustrine shale were uncovered from the rock matrix to reveal morphological details and were photographed with LM. Specimens were compared morphologically with extant material of related plants, and resulting images were processed minimally with Adobe Photoshop.Pivotal results. Specimens demonstrate an organography that is quite similar to that of modern onions and related forms. To our knowledge, this is the first description of plants showing a combination of bulbils and florets (representing asexual and sexual reproduction) among Paleogene plants. It also represents one of few reports among the fossil record of monocot plants similar to members of Amaryllidaceae.Conclusions. Scapes bearing flowers and bulbils within a spathe similar to those of some modern Amaryllidaceae, associated flower buds, and a root-producing bulb indicate the presence of a distinctive monocot plant in the Republic flora of the latest early Eocene Okanogan Highlands, northeastern Washington. Along with other Republic plants with distinctive morphological features indicative of temperate floras (leaf dimorphism, possible hybridization), these fossils suggest that bulbil- and flower-bearing monocots with a combined asexual and sexual reproductive strategy were already well established among plants of Paleogene.
Abstract Species of Trillium in the subgenus Phyllantherum are either polymorphic for flower color, or monomorphic for flower color and related to a polymorphic species. This leads to the suggestion that polymorphic species may be the progenitors for monomorphic ones. For this to be true, it must be demonstrated that genetic divergence among flower morphs can occur within polymorphic populations. Genetic structure was assessed in a population of T. sessile that contains a polymorphism for flower color. A survey of 11 enzyme systems using starch gel electrophoresis revealed three polymorphic loci: 6PGD‐1, AAT‐1 and AAT‐2. Analysis of large and small scale spatial structure, stage classes, and flower color classes revealed significant genetic divergence in all instances. Spatial structure in the population is likely a result of genetic neighborhoods which can maintain populational variation via random genetic drift. Genetic divergence of the yellow flower color morph was probably initiated through genetic drift since the morph occurs in low frequencies. The results imply that the initial genetic divergence of species in the subgenus can arise within polymorphic populations.
A study of flavonoids occurring within a heterocyanic population of Trillium sessile was made to determine the chemical basis of a common floral color polymorphism in this species. In the study population, three floral color phenotypes (red, pink, yellow) are determined primarily by the presence or absence of anthocyanin compounds in the petal tissue, and secondarily by quantitative differences in the concentration of several flavonol glycosides. Petals of red phenotypes contain both cyanidin 3-arabinoside and 3-diarabinoside, petals of pink phenotypes contain only cyanidin 3-arabinoside, and petals of yellow phenotypes lack cyanidin entirely. Quercetin 3-0-glucoside, quercetin 3-0-arabinoglucoside, quercetin 3–0-arabinogalactoside, and quercetin 3-0-arabinogalactosyl, 7-0-glucoside occur in petals of all three phenotypes but differ in relative amounts. Petals of the red phenotype have mostly 3-0-biosides, but lesser amounts of both quercetin 3-0-glucoside and the 3,7-0-triglycoside. Petals of the pink phenotype contain relatively equal amounts of quercetin mono-, di-, and triglycosides. Petals of the yellow phenotypes contain mostly quercetin 3,7-0-triglycosides, and less mono- and di-glycosides. Small amounts of a quercetin tetraglycoside were detected in petals of both yellow and pink phenotypes, but not in red phenotypes. The enhancement of quercetin polyglycoside biosynthesis in yellow petal phenotypes is attributed to the shunting of dihydroflavonol precursors to synthesis of quercetin compounds when their conversion to anthocyanins is blocked genetically.
Polypodium virginianum comprises three morphologically similar cytotypes: diploid (2n = 74), triploid (2n = 111), and tetraploid (2n = 148). Previous cytological and morphological analyses suggested that tetraploid P. virginianum was actually of allopolyploid origin resulting from hybridization between diploid P. virginianum and another diploid Polypodium species. To test this, an electrophoretic investigation of diploid, triploid, and tetraploid populations of P. virginianum was undertaken. Analysis of eight enzymes showed 15 loci common to all three cytotypes. Fixed heterozygosity due to the presence of two additional isozymes was detected in triploid and tetraploid P. virginianum. This increase in isozyme number in the tetraploid is suggestive of the addition of two divergent genomes in its formation. One of the parental genomes involved in the formation of tetraploid P. virginianum clearly is diploid P. virginianum; the second parental genome appears to be P. amorphum. Electrophoretic data are in agreement with 1) an allopolyploid origin of tetraploid P. virginianum, and 2) formation of the triploid cytotype via hybridization between diploid and tetraploid P. virginianum.
A study of flavonoids occurring within a heterocyanic population of Trillium sessile was made to determine the chemical basis of a common floral color polymorphism in this species. In the study population, three floral color phenotypes (red, pink, yellow) are determined primarily by the presence or absence of anthocyanin compounds in the petal tissue, and secondarily by quantitative differences in the concentration of several flavonol glycosides. Petals of red phenotypes contain both cyanidin 3‐arabinoside and 3‐diarabinoside, petals of pink phenotypes contain only cyanidin 3‐arabinoside, and petals of yellow phenotypes lack cyanidin entirely. Quercetin 3‐0‐glucoside, quercetin 3‐0‐arabinoglucoside, quercetin 3–0‐arabinogalactoside, and quercetin 3‐0‐arabinogalactosyl, 7‐0‐glucoside occur in petals of all three phenotypes but differ in relative amounts. Petals of the red phenotype have mostly 3‐0‐biosides, but lesser amounts of both quercetin 3‐0‐glucoside and the 3,7‐0‐triglycoside. Petals of the pink phenotype contain relatively equal amounts of quercetin mono‐, di‐, and triglycosides. Petals of the yellow phenotypes contain mostly quercetin 3,7‐0‐triglycosides, and less mono‐ and di‐glycosides. Small amounts of a quercetin tetraglycoside were detected in petals of both yellow and pink phenotypes, but not in red phenotypes. The enhancement of quercetin polyglycoside biosynthesis in yellow petal phenotypes is attributed to the shunting of dihydroflavonol precursors to synthesis of quercetin compounds when their conversion to anthocyanins is blocked genetically.
