Fruit and seed ontogeny related to the seed behaviour of two tropical species of Caesalpinia (Leguminosae)

Caesalpinia echinata and C. ferrea var. ferrea have different seed behaviours and seed and fruit types. Comparison of the seed ontogeny and anatomy partly explained the differences in seed behaviour between these two species of Brazilian legumes; some differences were also related to fruit development. The seed coat in C. ferrea consisted of two layers of osteosclereids, as well as macrosclereids and fibres, to form a typical legume seed coat, whereas C. echinata had only macrosclereids and fibres. In C. echinata , the developing seed coat had paracytic stomata, a feature rarely found in legume seeds. These seed coat features may account for the low longevity of C. echinata seeds. The embryogeny was similar in both species, with no differences in the relationship between embryo growth and seed growth. The seeds of both species behaved as typical endospermic seeds, despite their different morphological classification (exendospermic orthodox seeds were described for C. echinata and endospermic orthodox seeds for C. ferrea ). Embryo growth in C. ferrea accelerated when the sclerenchyma of the pericarp was developing, whereas embryonic growth in C. echinata was associated with the conclusion of spine and secretory reservoir development in the pericarp. Other features observed included an endothelial layer that secreted mucilage in both species, a nucellar summit, which grew up into the micropyle, and a placental obturator that connected the ovarian tissue to the ovule in C. ferrea . © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 57–70.     

Phylogeny of the Afro-Madagascan Aristea (Iridaceae) revisited in the light of new data on pollen morphology

Scanning and electron microscopic studies of the pollen grains of several species of the sub-Saharan African and Madagascan genus Aristea of c . 50 species, supplement data from an earlier study and enable us to include these species in a phylogenetic analysis. TEM examination of a range of pollen grains of representative pollen types in Aristea makes it possible to reinterpret past SEM results so that apertures covered with exine masses and previously called sulculate, are now seen to be either zonasulculate or dizonasulculate. Revised and expanded data are combined in a matrix together with new data for seed morphology in the genus, which like the capsules is remarkably diverse, including angular seeds with reticulate sculpturing, lamellate or triangular-columnar seeds with smooth or reticulate surfaces and with smooth or papillate or areolate margins. This new phylogenetic analysis suggests that Aristea should remain treated as comprising three subgenera. In subgenus Eucapsulares we add a new section Latifolieae for A. latifolia , which seems an isolated relic restricted to the mountains of the Cape Region of South Africa, an area of winter rainfall. Species with similar unspecialized capsule and seed morphology occur only in eastern south and tropical Africa and Madagascar, but they have derived pollen morphology whereas the pollen of A. latifolia is plesiomorphic. This species appears to be the closest living ancestor of the genus. In subgenus Aristea we continue to recognize three sections, sect. Racemosae , sect. Singulares and sect. Aristea. Nesting of subgenus Pseudaristea within section Racemosae of subgenus Aristea is probably an artefact of the analysis and does not receive bootstrap support, and hence we continue to recognize this group of species at subgeneric rank.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 41–68.     

An unusual case of epigeal cryptocotylar germination in Rollinia salicifolia (Annonaceae)

An unusual case of epigeal cryptocotylar germination found in Rollinia salicifolia Schltdl. (Annonaceae) is described and is discussed in relation to the terminology used for germination studies. The terms cryptocotylar and phanerocotylar are used to describe the permanence of cotyledons within the seed coat or endocarp; the terms epigeal and hypogeal are used to refer the position of cotyledons in relation to ground level. The terms to describe position about ground level and permanence of cotyledons within the seed coat or endocarp are not used simultaneously in many papers, and some authors consider the terms cryptocotylar and hypogeal to be synonyms. Cases of epigeal cryptocotylar germination seem to be scarce in the literature. The morphological characters shown by R. salicifolia seeds and seedlings − a non-chlorophyllous embryo, abundant endosperm, thick woody seed coat, thickened hypocotyl and non-photosynthetic haustorial cotyledons − are closely related to its epigeal cryptocotylar germination. This is the first record of this type of germination in Argentina.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 53–56.     

Nuclear Replication Activity During Seed Development, Dormancy Breakage and Germination in Three Tree Species: Norway Maple (Acer platanoidesL.), Sycamore (Acer pseudoplatanusL.) and Cherry (Prunus aviumL.)

Flow cytometric analyses of nuclear DNA levels were carriedout during development, stratification and germination of dormantseeds from three tree species with contrasting characteristics.Norway maple (Acer platanoides) and sycamore (Acer pseudoplatanus)have orthodox (desiccation-tolerant) and recalcitrant (desiccation-sensitive)storage behaviours, respectively, and require only a periodof cold to break dormancy, whereas, orthodox cherry (Prunusavium) seeds require an initial warm period before cold stratificationto fully stimulate germination. Whole embryos and radicle tipsof both Norway maple and sycamore were found to have stablehigh levels of 4C DNA during the latter stages of developmentand both contained nuclei arrested at the 2C and 4C levels atmaturity. Mature cherry embryos had nuclei predominantly arrestedat the 2C level. This suggests that the acquisition of desiccationtolerance is not correlated with the arrest of the cell cycleat any particular nuclear DNA level. Neither DNA replicationin radicle cells nor germination occurred when seeds were maintainedmoist at a constant 20 °C. However, in the late stages ofcold treatment during stratification, nuclear DNA levels inradicle cells changed in advance of radicle emergence in theorthodox Norway maple and cherry, whereas in the recalcitrantsycamore, change was not recorded until after radicle emergence.These results show that DNA replication has potential use asan indicator of the progress of tree seeds through stratificationtreatments used to break some types of dormancy. The ways inwhich this indicator could be exploited for seed quality andperformance testing are discussed.Copyright 1998 Annals of BotanyCompany Norway maple,Acer platanoidesL., sycamore,Acer pseudoplatanusL., cherry,Prunus aviumL., DNA replication, flow cytometry, seed dormancy, stratification     

Seed micromorphology in the genus Neotinea Rchb.f. (Orchidaceae, Orchidinae)

The ultrastructure of testa seed in the genus Neotinea (Orchidaceae, Orchidinae) was examined for the first time. The morphology of the seed and of the anticlinal and periclinal walls was analysed by scanning electron microscopy. Quantitative data concerning the length and width of the seed and embryo, seed and embryo volume, free air space, and number of cells along the longitudinal axis are presented. In all species, the seeds are fusiform in shape with transverse ridges on the inner periclinal walls. This ornamentation pattern is characteristic for the genus Neotinea . It is a good diagnostic value supporting the monophyly of this genus, which has recently been proposed by several authors.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 133–140.     

Fruits and seeds of Ruppia (Potamogetonaceae) from the Pliocene of Yushe Basin, Shanxi, northern China and their ecological implications

Numerous fruits and seeds of Ruppia are reported from the Upper Pliocene (2.3–3.5 Myr ago) Zhangcun Formation in Yushe Basin, Shanxi, northern China. They are the first fossil Ruppia from China and demonstrate the importance of fruit and seed fossils in recording genera not represented by fossil leaves. These Ruppia are characterized by possessing a small oval endocarp, smooth endocarp surface, distinct elliptical external depressions, distinct apical mucro, slightly curved seed shape and conspicuous globose hilum. A new species, R. yushensis Zhao, Collinson and Li, is described from these endocarp and seed features. Comparison with the two European Miocene species, R. palaeomaritima Negru and R. maritime-miocenica Szafer, indicates the existence at that time of three different geographical and stratigraphical species. R. yushensis constitutes the first Pliocene record of Ruppia and extends the range of fossils of this genus from Europe to eastern Asia. R. yushensis is the only aquatic plant in the uppermost middle part of the Zhangcun Formation. This monotypic occurrence indicates a brackish, clear, tranquil and shallow lake in this region in the Late Pliocene. The smooth endocarp surface further suggests a warm temperate or temperate palaeoclimate.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 317–329.     

Influence of selfing and maternal effects on life-cycle traits and dispersal ability in the herb Hypochaeris radicata (Asteraceae)

The ecological and evolutionary implications of dispersal are many. Pollination type and maternal effects may affect plant fitness traits, including life-cycle traits as well as dispersal ability. This study investigated the joint influence of pollination type and maternal effects on both life-cycle traits and dispersal ability in the herb Hypochaeris radicata . We conducted experimental crosses to obtain selfed and outcrossed progeny. Individual seeds and their pappuses were measured to determine seed terminal velocity. Seed size was also used to assess maternal effects. Selfing dramatically decreased seed set, indicating that H. radicata is self-incompatible. However, the few selfed seeds produced outperformed outcrossed seeds in seed size and flowering probability, surely as a result of an effective reallocation of resources among selfed seeds. None of the life-cycle traits was affected by seed size, the estimate of maternal effects. Selfed seeds were larger and bore a smaller pappus than outcrossed seeds. As a result, dispersal ability was lower for selfed than outcrossed seeds. Several factors, such as the low proportion of plants that produced selfed seeds, the low number of selfed seeds produced per plant, and the lack of self-fertility mechanisms might act in concert to prevent the evolution of selfing in H. radicata .  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 163–170.     

Assessing frequency-dependent seed size selection: a field experiment

Seed size is a life history attribute that affects the probability of seed predation, and therefore affects plant fitness. Compared with smaller seeds, those with large size should be more attractive to predators, as they constitute a more profitable food item because of higher energetic and/or nutrient content. However, predator preferences may be frequency-dependent in the sense that they may be modulated by the relative abundance of alternative seeds of different sizes. We set up a field experiment to evaluate frequency-dependent seed predation using seeds of Cryptocarya alba (Lauraceae), at La Campana National Park in central Chile. Predators (rodents and birds) preferentially consumed large seeds in an antiapostatic manner. These selective responses were maintained throughout the experiment and seed selection by predators was not affected by previous seed consumption. Our results suggest that (a) large seeds are very profitable food items actively sought by seed predators even at low relative abundance, (b) seed selection is expressed in a short time scale and (c) seed predators, by consuming large seeds consistently, have the potential to modify significantly the quality of plant progeny.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 307–312.     

The pollen morphology of Phyllanthus (Euphorbiaceae) section Choretropsis

The pollen grain morphology of the eight South American species of the genus Phyllanthus , subgenus Phyllanthus , section Choretropsis , endemic to Brazil, was investigated using light and scanning electron microscopy. The high homogeneity in pollen shape, as well as aperture number and configuration, allowed the definition of a basic pollen type for this section, viz. prolate spheroidal or subprolate, zonocolporate with 4–5 invaginated colpi, sexine reticulate. Two subtypes have been observed, based on pollen grain apertures and exine sculpture. The first subtype is characterized by straight and narrow colpi provided with costae, lalongate endoapertures and a reticulum of rectilineous muri as in P. choretroides and P. spartioides . The second subtype has wider colpi without costae, circular endoapertures and a reticulum with curvilineous muri as in P. flagelliformis , P. goianensis and P. scoparius , or curvilineous-rectilineous muri as in P. angustissimus , P. gladiatus and P. klotzschianus . It was demonstrated that the pollen shape and the number of colpi varied within and between some of the species. The results suggest that pollen grain morphology, in association with plant architecture and the presence of phylloclades, constitute additional evidence to delimit the species of the section Choretropsis and to further understand their evolutionary origin within the genus Phyllanthus.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 243–250.     

Seed germination of the carnivorous plant Byblis gigantea (Byblidaceae) is cued by warm stratification and karrikinolide

Byblidaceae is one of the most poorly studied carnivorous plant families, with seed dormancy and germination biology remaining unresolved. This knowledge deficit has significant conservation and management implications, particularly as the most southerly distributed species, the south‐west Western Australian endemic Byblis gigantea, is listed as critically endangered. This study examined the ecophysiology of seed dormancy and germination in B. gigantea in concert with a study of the population dynamics of a single plant community. Mass seedling emergence and plant establishment were observed after a wildfire in 2007 in the natural population, followed by a rapid decline in mature individuals (91%) over a 4‐year monitoring period, with almost no inter‐fire recruitment (1.4% of all emergence) observed. Seeds possessed a fully developed embryo, and the germination characteristics of fresh seeds classified them as showing physiological dormancy. Seed dormancy was partially alleviated by warm stratification (30 °C) for 8 weeks prior to incubation at 15 °C, with c. 40% germination observed. With the additional exposure of seeds to the germination‐active chemical in smoke, karrikinolide, the germination of warm‐stratified seeds increased to 89%. Seeds also displayed orthodox storage behaviour and appeared to be amenable to long‐term seed banking for conservation. These results present the first observation of the stimulation of the germination of a carnivorous plant by a smoke‐derived compound. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172 , 143–152.     

Genome redundancy and plasticity within ancient and recent Brassica crop species

The crop species within the genus Brassica have highly replicated genomes. Three base 'diploid' species, Brassica oleracea , B. nigra and B. rapa , are likely ancient polyploids, and three derived allopolyploid species, B. carinata , B. juncea and B. napus , are created from the interspecific hybridization of these base genomes. The base Brassica genome is thought to have hexaploid ancestry, and both recent and ancient polyploidization events have been proposed to generate a large number of genome rearrangements and novel genetic variation for important traits. Here, we revisit and refine these hypotheses. We have examined the B. oleracea linkage map using the Arabidopsis thaliana genome sequence as a template and suggest that there is strong evidence for genome replication and rearrangement within the base Brassicas, but less evidence for genome triplication. We show that novel phenotypic variation within the base Brassicas can be achieved by replication of a single gene, BrFLC , that acts additively to influence flowering time. Within the derived allopolyploids, intergenomic heterozygosity is associated with higher seed yields. Some studies have reported that de novo genomic variation occurs within derived polyploid genomes, whereas other studies have not detected these changes. We discuss reasons for these different findings. Large translocations and tetrasomic inheritance can explain some but not all genomic changes within the polyploids. Transpositions and other small-scale sequence changes probably also have contributed to genomic novelty. Our results have shown that the Brassica genomes are remarkably plastic, and that polyploidy generates novel genetic variation through gene duplication, intergenomic heterozygosity and perhaps epigenetic change.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 665–674.     

Reproductive ecology of the endemic Lecocarpus pinnatifidus (Asteraceae) in an isolated population in the Galápagos Islands

Lecocarpus pinnatifidus is an endemic member of the Asteraceae occurring on only one island in the Galápagos archipelago. The capitula are large with female ray florets and male disc florets. They are self-compatible but this study suggests fruit set is pollen limited. Visits from Xylocopa darwini and other larger insect pollinators are rare, and small insects seem to be the main pollinators. Small insects carry few pollen grains and most likely mediate self-pollinations. Self-compatibility and seed set after selfing are the most common reproductive strategy in the Galápagos Islands and L. pinnatifidus seemingly fits well into this group.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 171–180.     

Noncorrelated evolution between herbivore- and pollinator-linked features in Aristolochia chilensis (Aristolochiaceae)

The effect of mutualists (i.e. pollinators) and antagonists (i.e. herbivores) can have non-additive effects on plant fitness. This is often interpreted as evidence for correlated evolution on a suite of traits leading to an increase and decrease of the interaction of plants with mutualists and antagonists, respectively. This situation has been found to prevail in plants that have large floral and fruit displays but are not limited by pollinators for seed set. We suggest the alternative hypothesis, where plants limited by pollinators for seed set (e.g. deceit-pollinated plants) exhibit additive effects of pollinators and herbivores on fitness (i.e. noncorrelated evolution). Using a 2 × 2 factorial design, we tested this hypothesis by solely and simultaneously evaluating the effects of pollinators and the single herbivore, Battus polydamas archidamas , on female reproductive success of Aristolochia chilensis . Plants exposed to herbivores presented 2.6-fold greater herbivory than plants that excluded them. In addition, plants exposed to pollinators showed strong limitation by pollinators for seed set compared with other plants of the genus Aristolochia. However, only pollinators had a significant effect on fruit and seed set because plants that excluded them did not set fruits or seeds. Furthermore, herbivores and pollinators exerted additive effects on fruit and seed production. Collectively, these results indicate that herbivore- and pollinator-linked traits in A. chilensis exhibit noncorrelated evolution.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 239–245.     

Transfer cells in the seeds of Boraginales

The presence of transfer cells (TCs) in the seeds of Boraginales (Boraginaceae s.s. , Hydrophyllaceae, Heliotropiaceae, Ehretiaceae, Cordiaceae and Lennoaceae) has been reported but has not hitherto been studied systematically. This study, surveying the seed anatomy of 50 species of Boraginales, demonstrates that in Heliotropiaceae, Cordiaceae, Ehretiaceae and Lennoaceae, TCs are found in an uninterrupted course from the placenta via the funicle to the seed coat. These families are characterized by indehiscent fruits with a protective endocarp. The TCs may act as a sponge, thus promoting rapid germination when sufficient water is available. In Hydrophyllaceae, which have capsular fruits, TCs are often found but have a different structure and are restricted to the seed coat. Boraginaceae s.s. on the other hand are characterized by a complete absence of TCs in their seeds. The presence of TCs in seeds is considered as a synapomorphic trait and appears to be phylogenetically informative.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 155−164.     

Seed dormancy and germination in Jeffersonia dubia (Berberidaceae) as affected by temperature and gibberellic acid

The genus Jeffersonia, which contains only two species, has a trans‐Atlantic disjunct distribution. The aims of this study were to determine the requirements for breaking dormancy and germination of J. dubia seeds and to compare its dormancy characteristics with those of the congener in eastern North America. Ripe seeds of J. dubia contain an underdeveloped embryo and were permeable to water. In nature, seeds were dispersed in May, while embryos began to grow in September, and were fully elongated by late November. Germination started in March of the next year, and seeds emerged as seedlings soon after germination. In laboratory experiments, incubation at high temperatures (25 °C, 25/15 °C) for at least 8 weeks was required to initiate embryo growth, while a transfer to moderate temperatures (20/10 °C, 15/6 °C) was needed for the completion of embryo growth. At least 8 weeks at 5 °C was effective in overcoming physiological dormancy and for germination in seeds after the embryos had fully elongated. Thus, both high and low temperatures were essential to break dormancy. Gibberellic acid (GA₃) treatment could substitute for the high temperature requirement, but not for the low temperature requirement. Based on the dormancy‐breaking requirements, it is confirmed that the seeds have deep simple morphophysiological dormancy. This dormancy type is similar to that of seeds of the eastern North American species J. diphylla. Although seeds require 10–11 months from seed dispersal to germination in nature, under controlled conditions they required only 3 months after treatment with 1000 mg·l^?1 GA₃, followed by incubation at 15/6 °C. This represents practical knowledge for propagation of these plants from seed.     

The relationship of Sophora sect. Edwardsia (Fabaceae) to Sophora tomentosa, the type species of the genus Sophora, observed from DNA sequence data and morphological characters

Sophora tomentosa , the type species of the genus Sophora , is shown by phylogenetic analyses of rbc L and ITS sequence data to be sister to Sophora sect. Edwardsia . S. tomentosa and most of the species from sect. Edwardsia share hypogeal germination, exstipulate leaves, and terete filaments. These species have buoyant seeds, and are distributed by ocean currents throughout the pantropics ( S. tomentosa ) and around southern temperate oceanic islands (sect. Edwardsia ). S. tomentosa differs from the species of sect. Edwardsia by its frutescent growth habit, terminal elongate inflorescence and smooth-walled legume. S. macrocarpa is unusual in sect. Edwardsia as its leaves have stipules, the filaments are winged, and the legume is smooth-walled.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 439–446.     

Changes in abscisic acid levels in embryo axes of Norway maple and sycamore seeds during maturation and dehydration

Changes in the abscisic acid (ABA) levels in embryo axes of seeds, belonging to the orthodox (Norway maple — Acer platanoides L.) and recalcitrant (sycamore — Acer pseudoplatanus L.) categories, were investigated throughout maturation using an ELISA (enzyme-linked immunosorbent assay) test. Concentration of ABA in embryo axes substantially differed depending on species and sampling date. ABA was always higher in Norway maple except at the end of seed maturation when ABA content was similar in both species. During maturation ABA decreased in both species but the decline was more marked in Norway maple than in sycamore (11 vs. 3 fold). These species also differed in the pattern of ABA changes, which in sycamore embryo axes was very regular, while in Norway maple a sharp decrease was recorded after acquisition by the seeds of tolerance to desiccation. Dehydration of embryo axes of Norway maple caused a further significant decrease of ABA level. In contrast, in dehydrated sycamore embryo axes ABA content did not decrease, but slightly increased. The role of ABA in desiccation tolerance and dormancy of Norway maple and sycamore seeds is discussed.     

Abortive seed development in Ulmus minor (Ulmaceae)

Three genotypes of field elm ( Ulmus minor ) were studied to determine the structural basis of seed abortion in this species. In the non-abortive control, P-VV1, the pattern of seed development is similar to many flowering plants. The embryo progresses through defined morphological stages leading to developmental arrest as the seed matures. Storage products are abundant within embryo cells. Endosperm development is similar to the nuclear type; however, a more extensive cellularization of the endosperm occurs prior to it being crushed by the expanding embryo. For the abortive genotypes, M-SF1 and V-JR1, abnormalities in endosperm development are found. This is judged by the early cellularization and the massive synthesis of the PAS-positive material in the cellular endosperm. In these abortive genotypes, embryo development is delayed and storage products failed to accumulate within embryo cells. After seed desiccation, no living embryo tissue remains within the seed coat in the abortive genotypes.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 455–467.     

Seed coat morphology of Aizoaceae–Sesuvioideae, Gisekiaceae and Molluginaceae and its systematic significance

Macro- and micromorphological characters of the seeds of 32 species belonging to Aizoaceae (26 species), Gisekiaceae (one species) and Molluginaceae (five species) were analysed for their taxonomic value. Seed morphology is found to be of considerable taxonomic value within the taxa investigated, although additional criteria are usually necessary for distinguishing the species. However, a subgroup of Trianthema , consisting of T. cussackiana , T. megasperma , T. pilosa , T. rhynchocalyptra and T. oxycalyptra var. oxycalyptra (Aizoaceae) shares the synapomorphy of seeds with scattered idioblast cells (papillae). There is little infrageneric variation within Sesuvium and Zaleya in contrast to Trianthema , whose seeds are considerably polymorphic. The fairly different seed structures found in Aizoaceae s.s . and Molluginaceae support their treatment as two distinct families. However, the position of Lineum (Molluginaceae) remains uncertain. Moreover, seed characters support the independence of Gisekia (Gisekiaceae) in a family of its own.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 189–206.     

Seed size variation within Zostera marina L. (Zosteraceae)

In 1997 and 1998 seeds were collected from the seagrass, Zostera marina L. (Zosteraceae) from Long Island, New York, USA (var. typica ), Shaw Island, Washington, USA (var. latifolia ) and Izembek Lagoon, Alaska, USA (var. izembekensis ) to determine if seed size varied between the varieties, if seed size varied within the same variety, and if the relationship between seed length and seed weight was linear. Measurements of seed length revealed statistically significant differences in this metric between varieties associated with smaller intertidal plants (var. typica and var. izembekensis ) and larger plants from the subtidal region (var. latifolia ). It was also found that seed length varied within the same variety and verified that the cross-sectional shape of these seeds was primarily elliptical. Using seed cross-sectional area and weight from a randomly selected batch of seeds from the three locations sampled in 1998, a linear model was created to determine seed weight and seeds from var. latifolia were found to be heavier than seeds from var. typica . The potential advantage of heavy seeds for subtidal seeds in search of safe sites is discussed, together with the merit of using the model to calculate the weight of other elliptical seeds within the Zosteraceae and other seagrass families.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 281–288.