Roxburgh was right: Aponogeton microphyllus and Aponogeton undulatus are distinct species.

Aponogeton microphyllus, previously placed under the synonymy of A. undulatus, is recognized here as a distinct species based on morphology, chromosome number, and molecular phylogenetics (nuclear ribosomal internal transcribed (ITS) spacer region). Observations on the type and live specimens revealed morphological differences between the two species. Aponogeton microphyllus flowered regularly and set seeds. Aponogeton undulatus flowered rarely, did not set seeds, but showed formation of young plantlets on the inflorescence axis. Similarly, different chromosome numbers were recorded in Aponogeton microphyllus and the two forms of A. undulatus, viz., AF1 and AF2, which occur in distinct populations. Aponogeton microphyllus exhibited polysomaty with root-tip cells showing 2n=40, 42, and 44 chromosomes. The two forms of A. undulatus, AF1 and AF2, showed 2n=84 and 86 chromosomes, respectively. Based on the ITS data, both species occupied two separate clades. Plastid trnK intron region indicated a close relationship between both species. Our study suggests the need for comprehensive phylogenetic analyses of A. undulatus across its distribution range based on more advanced techniques such as highthroughput sequencing data to understand the A. undulatus species complex and to detect natural hybrids of this species.

Revised molecular phylogeny, global biogeography, and diversification of palms subfamily Coryphoideae (Arecaceae) based on low copy nuclear and plastid regions.

Coryphoideae are palmate-leaved palms from the family Arecaceae consisting of 46 genera representing 421 species. Although several phylogenetic analyses based on different genomic regions have been carried out on Coryphoideae, a fully resolved molecular phylogenetic tree has not been reported yet. To achieve this, we applied two phylogenetic reconstruction methods: Maximum Likelihood and Bayesian Inference, using amplified sampling by retrieving chloroplast and nuclear DNA sequences from NCBI and adding newly produced sequences from Indian accession into the dataset. The same dataset (chloroplast + nuclear DNA sequences) was used to estimate divergence times and the evolutionary history of Coryphoideae with a Bayesian uncorrelated, lognormal relaxed-clock approach and a Statistical Divergence-Vicariance Analysis method, respectively. The phylogenetic analyses based on a combined chloroplast and nuclear DNA sequence dataset showed well-resolved relationships within the subfamily. Both phylogenetic trees divide Coryphoideae into two main groups: CSPT (Crysophileae, Sabaleae, Phoeniceae, and Trachycarpeae) and the Syncarpous group. These main groups are segregated into eight tribes (Trachycarpeae, Phoeniceae, Sabaleae, Crysophileae, Borasseae, Corypheae, Caryoteae, and Chuniophoeniceae) and four subtribes (Rhapidine, Livistoninae, Hyphaeninae, and Lataniinae) with strong support-values. Most previously unresolved and doubtful relationships within tribes Trachycarpeae and Crysophilieae are now resolved and well-supported. The reconstructed phylogenetic trees support all previous systematic revisions of the subfamily. All Indian sampled species of Arenga, Bentinckia, Hyphaene, and Trachycarpus show close relation with their respective congeneric species. Molecular dating results and integration of biogeography suggest that Coryphoideae originated in Laurasia at ~95.12 Ma and then diverged into the tropical and subtropical regions of the whole world. This study offers the correct combination of nuclear and plastid regions to test the current and future systematic revisions.

Pollen Production of Selected Grass Species in Russia and India at the Levels of Anther, Flower and Inflorescence.

Grasses produce large amounts of pollen and are among the main causes of pollen allergy worldwide. Quantification of the roles of individual grass species in airborne pollen is an important task, because morphologically indistinguishable pollen grains of different species may differ in allergenicity. This requires knowledge of the pollen production of individual grass species; however, accumulated data are insufficient in this respect. Attempting to fill this gap, we studied pollen production per inflorescence in 29 grass species which are widespread in Middle Russia and India. Pollen production per inflorescence is determined by the number of grains per anther, the number of flowers in a spikelet and the number of spikelets per inflorescence, with the latter parameter being the most variable. We support the hypothesis that pollen production per inflorescence differs significantly between annual and perennial grasses. The greater pollen production of perennials can be interpreted as a tendency to guarantee cross-fertilization of species with self-incompatibility. The inferred pollen/ovule (P/O) ratios suggest the occurrence of facultative xenogamy in all annuals and obligate xenogamy in most perennials in the present dataset, though some self-incompatible annuals exist outside our sampling. Earlier data indicated that the P/O ratio of the annual cereal crop rye (Secale cereale) is higher than in any annual or perennial species sampled here. A ratio of pollen production to seed set (P/S ratio) is suggested to be another efficient parameter in reproductive biology of grasses. We highlight a need for detailed studies of reproductive biology in grasses that include both pollen and seed production. We found a correlation between pollen production per anther and anther length. A rough approximation of c. 1000 pollen grains per 1 mm of the length of an anther provides an instrument for estimates of pollen production in plant communities.

Stability Despite Reduction: Flower Structure, Patterns of Receptacle Elongation and Organ Fusion in Eriocaulon (Eriocaulaceae: Poales).

Eriocaulaceae (Poales) differ from potentially related Xyridaceae in pattern of floral organ arrangement relative to subtending bract (with median sepal adaxial). Some Eriocaulaceae possess reduced and non-trimerous perianth, but developmental data are insufficient. We conducted a SEM investigation of flower development in three species of Eriocaulon to understand whether organ number and arrangement are stable in E. redactum, a species with a highly reduced calyx and reportedly missing corolla. Early flower development is similar in all three species. Male and female flowers are indistinguishable at early stages. Despite earlier reports, both floral types uniformly possess three congenitally united sepals and three petals in E. redactum. Petals and inner stamens develop from common primordia. We assume that scanning electron microscopy should be used in taxonomic accounts of Eriocaulon to assess organ number and arrangement. Two types of corolla reduction are found in Eriocaulaceae: suppression and complete loss of petals. Common petal-stamen primordia in Eriocaulon do not co-occur with delayed receptacle expansion as in other monocots but are associated with retarded petal growth. The 'reverse' flower orientation of Eriocaulon is probably due to strictly transversal lateral sepals. Gynoecium development indicates similarities of Eriocaulaceae with restiids and graminids rather than with Xyridaceae.

Multidimensional Studies of Pancratium parvum Dalzell Against Acetylcholinesterase: A Potential Enzyme for Alzheimer's Management.

Objective:Pancratium L. (Amaryllidaceae J.St. Hil.) is a monocot genus with bulbous habitat and about 20 species worldwide have significant medicinal properties. The present envision aims to investigate the potential ability of Pancratium species for acetylcholinesterase (AChE) inhibition as a remedy for Alzheimer disease (AD). Different Pancratium species were screened for the inhibition of AChE enzyme from various localities across India. Prominent species was further studied for anti-inflammatory, antioxidant, metal chelating and UHPLC-QTOF-MS analysis.Methods: Nine different species collected across India were examined for AChE inhibition and for binding affinity studies using Surface Plasmon Resonance (SPR). Highest inhibition species was subjected to Response Surface Methodology (RSM) to accomplish the effective conditions for maximum extraction of phytomolecules in accordance with the inhibition of the AChE. Further, extract under optimized conditions were used to study anti-inflammatory, antioxidant, metal chelating and UHPLC-QTOF-MS analysis for tentative identification of phytomolecules.Results: Amongst different species collected, P. parvum Dalzell exhibited maximum inhibition 93.30 ± 1.71% with promising IC50 20 ± 0.22 µg/ml value. In addition, binding affinity toward AChE and ß plaques using SPR technique showed a higher binding response toward the enzyme. RSM study resulted that water extracts at 50 °C and 5.46 hours heating executed maximum inhibition. Other studies showed prominent anti-inflammatory and metal chelating ability with low antioxidant property.Conclusion: By using UHPLC-QTOF-MS compounds were tentatively identified for the concerned activities mentioned above. This work reports for accounting the detailed study of P. parvum and which can be further entailed for the treatment of various neurological disorders.

In vitro regeneration approaches for restoration of Ceropegia mohanramii-an endemic and critically endangered asclepiad.

The study aimed to develop an efficient, rapid, and large-scale in vitro regeneration system for propagation, conservation, and restoration of an endemic and critically endangered herb, Ceropegia mohanramii. The cultures were established using nodal explants on Murashige and Skoog's (MS) medium supplemented with 6-benzylaminopurine (BAP: 1.0 mg/l). Nodal buds cultured on MS medium supplemented with BAP (2.0 mg/l) along with indole-3-butyric acid (IBA, 0.5 mg/l) resulted with production of maximum number of shoots (17.1 ± 1.2) in hundred percent of the cultures. MS medium supplemented with BAP (2.0 mg/l) along with diverse concentrations of indole-3acetic acid (IAA) promoted the in vitro flowering. In vitro regenerated shoots were transferred to one-half MS medium fortified with singular supplementation of auxins, where IBA (1.5 mg/l) served optimal for production of maximum number of roots (5.7 ± 0.6). In vitro derived plantlets were hardened under controlled conditions in a glasshouse and subsequently transferred to soil. Over 1200 saplings were transplanted to eight different localities of the Western Ghats where over 76% survival is recorded after 1 year of transplantation.

Reconstruction of molecular phylogeny of closely related Amorphophallus species of India using plastid DNA marker and fingerprinting approaches.

Plastid DNA markers sequencing and DNA fingerprinting approaches were used and compared for resolving molecular phylogeny of closely related, previously unexplored Amorphophallus species of India. The utility of individual plastid markers namely rbcL, matK, trnH-psbA, trnLC-trnLD, their combined dataset and two fingerprinting techniques viz. RAPD and ISSR were tested for their efficacy to resolves Amorphophallus species into three sections specific clades namely Rhaphiophallus, Conophallus and Amorphophallus. In the present study, sequences of these four plastid DNA regions as well as RAPD and ISSR profiles of 16 Amorphophallus species together with six varieties of two species were generated and analyzed. Maximum likelihood and Bayesian Inference based construction of phylogenetic trees indicated that among the four plastid DNA regions tested individually and their combined dataset, rbcL was found best suited for resolving closely related Amorphophallus species into section specific clades. When analyzed individually, rbcL exhibited better discrimination ability than matK, trnH-psbA, trnLC-trnLD and combination of all four tested plastid markers. Among two fingerprinting techniques used, the resolution of Amorphophallus species using RAPD was better than ISSR and combination of RAPD +ISSR and in congruence with resolution based on rbcL.

Grass plastomes reveal unexpected paraphyly with endemic species of Micrairoideae from India and new haplotype markers in Arundinoideae.

PREMISE OF THE STUDY: We investigated the little-studied Arundinoideae/Micrairoideae clade of grasses with an innovative plastome phylogenomic approach. This method gives robust results for taxa of uncertain phylogenetic placement. Arundinoideae comprise ∼45 species, although historically was much larger. Arundinoideae is notable for the widely invasive Phragmites australis. Micrairoideae comprise nine genera and ∼200 species. Some are threatened with extinction, including Hubbardia, some Isachne spp., and Limnopoa. Two micrairoid genera, Eriachne and Pheidochloa, exhibit C4 photosynthesis in this otherwise C3 subfamily and represent an independent origin of the C4 pathway among grasses. METHODS: Five new plastomes were sequenced with next-generation sequencing-by-synthesis methods. Plastomes were assembled by de novo methods and phylogenetically analyzed with eight other recently published arundinoid or micrairoid plastomes and 11 outgroup species. Stable carbon isotope ratios were determined for micrairoid and arundinoid species to investigate ambiguities in the proxy evidence for C4 photosynthesis. KEY RESULTS: Phylogenomic analyses showed strong support for ingroup nodes in the Arundinoideae/Micrairoideae subtree, including a paraphyletic clade of Hubbardieae with Isachneae. Anatomical, biochemical, and positively selected sites data are ambiguous with regard to the photosynthetic pathways in Micrairoideae. Species of Hubbardia, Isachne, and Limnopoa were definitively shown by δ13C measurements to be C3 and Eriachne to be C4. CONCLUSIONS: Our plastome phylogenomic analyses for Micrairoideae are the first phylogenetic results to indicate paraphyly between Isachneae and Hubbardieae. The definitive δ13C data for four genera of Micrairoideae indicates the breadth of variation possible in the proxy evidence for photosynthetic pathways of both C3 and C4 taxa.

Evaluation of L-dopa, proximate composition with in vitro anti-inflammatory and antioxidant activity of Mucuna macrocarpa beans: A future drug for Parkinson treatment

Objective:To investigate L-3,4-dihydroxyphenylalanine (L-dopa,anfi-Parkinson drug),anti-inflammatory activity,proximate nutritional composition and antioxidant potential of Mucuna macrocarpa (M.macrocarpa) beans.Methods:L-dopa content was determined and quantified by high performance thin layer chromatography and reversed phase high-performance liquid chromatography (RPHPLC) methods.Anti-inflammatory activity was performed by in vitro protein denaturation inhibition and human red blood cell membrane stabilisation activity.Proximate composition and elemental analysis were also investigated.The antioxidant potential (2,2-diphenyl-1-picrylhydrazyl,N-N-dimethyl-phenylenediamine and ferric-reducing antioxidant power) of M.macrocarpa beans were evaluated by using different extraction solvents.The RP-HPLC analysis also quantified significant phenolics such as gallic acid,tannic acid,p-hydroxybenzoic acid and p-coumaric acid.Results:RP-HPLC quantification revealed that M.macrocarpa beans contain a high level of L-dopa [(115.41 ± 0.985) mg/g] which was the highest among the Mucuna species from Indian sub-continent.Water extract of seed powder showed strong antiinflammatory and antioxidant potential.Proximate composition of M.macrocarpa beans revealed numerous nutritional and anti-nutritional components.RP-HPLC analysis of major phenolics such as tannic acid (43.795 mg/g),gallic acid (0.864 mg/g),p-coumafic acid (0.364 mg/g) and p-hydroxybenzoic acid (0.036 mg/g) quantified successfully from M.macrocarpa beans respectively.Conclusions:This study suggests that M.macrocarpa is a potential source of L-dopa with promising anti-inflammatory,antioxidant and nutritional benefits.

Assessment of genetic diversity in Mucuna species of India using randomly amplified polymorphic DNA and inter simple sequence repeat markers.

Genus Mucuna which is native to China and Eastern India comprises of perennial climbing legume with long slender branches, trifoliate leaves and bear green or brown pod covered with soft or rigid hairs that cause intense irritation. The plants of this genus are agronomically and economically important and commercially cultivated in India, China and other regions of the world. The high degrees of taxonomical confusions exist in Mucuna species that make authentic identification and classification difficult. In the present study, the genetic diversity among the 59 accessions of six species and three varieties of M. pruriens has been assessed using DNA fingerprinting based molecular markers techniques namely randomly amplified polymorphic DNA (RAPD), inter simple sequence repeats (ISSR) and combined dataset of RAPD and ISSR. Also, genetic relationship among two endemic species of Mucuna namely M. imbricata and M. macrocarpa and two varieties namely IIHR hybrid (MHR) and Dhanwantari (MD) with other species under study was investigated by using cluster analysis and principal coordinate analysis. The cluster analysis of RAPD, ISSR and combined dataset of RAPD and ISSR clearly demonstrated the existence of high interspecific variation than intra-specific variation in genus Mucuna. The utility and efficacy of RAPD and ISSR for the study of intra species and interspecies genetic diversity was evident from AMOVA and PCoA analysis. This study demonstrates the genetic diversity in Mucuna species and indicates that these markers could be successfully used to assess genetic variation among the accessions of Mucuna species.

Phylogenetic analysis, genetic diversity and relationships between the recently segregated species of Corynandra and Cleoserrata from the genus Cleome using DNA barcoding and molecular markers.

Cleome is the largest genus in the family Cleomaceae and it is known for its various medicinal properties. Recently, some species from the Cleome genus (Cleome viscosa, Cleome chelidonii, Cleome felina and Cleome speciosa) are split into genera Corynandra (Corynandra viscosa, Corynandra chelidonii, Corynandra felina), and Cleoserrata (Cleoserrata speciosa). The objective of this study was to obtain DNA barcodes for these species for their accurate identification and determining phylogenetic relationships. Out of 10 screened barcoding regions, rbcL, matK and ITS1 regions showed higher PCR efficiency and sequencing success. This study added matK, rbcL and ITS1 barcodes for the identification of Corynandra chelidonii, Corynandra felina, Cleome simplicifolia and Cleome aspera species in existing barcode data. Corynandra chelidonii and Corynandra felina species belong to the Corynandra genus, but they are not grouped with the Corynandra viscosa species, however clustered with the Cleome species. Molecular marker analysis showed 100% polymorphism among the studied plant samples. Diversity indices for molecular markers were ranged from He=0.1115-0.1714 and I=0.2268-0.2700, which indicates a significant amount of genetic diversity among studied species. Discrimination of the Cleome and Corynandra species from Cleoserrata speciosa was obtained by two RAPD primers (OPA-4 and RAPD-17) and two ISSR primers (ISSR-1 and ISSR-2). RAPD and ISSR markers are useful for the genetic characterization of these studied species. The present investigation will be helpful to understand the relationships of Cleome lineages with Corynandra and Cleoserrata species.

Analysis of genetic variability in endemic medicinal plants of genus Chlorophytum from the Indian subcontinent using amplified fragment length polymorphism marker.

The genus Chlorophytum consists of medicinally important species like Chlorophytum borivilianum, C. tuberosum and C. attenuatum. Uncontrolled harvest of this plant from wild habitat due to its high commercial value made the species of this genus be listed in the Red Data Book of Indian plants as an endangered species. In India, approximately nineteen species of Chlorophytum are found; out of these, only C. borivilianum is cultivated commercially. The objective of this study was to measure genetic diversity, population structure and phylogenetic relationship among the species using Amplified Fragment Length Polymorphisms (AFLP). Fifteen pairs of primer (out of 64 primer pairs screened) were used to analyse the genetic diversity in eighteen species of genus Chlorophytum. Cluster analysis, estimation of the gene flow among the species and of the phylogeographic distribution of this genus were carried out using an AFLP data matrix. A high level of genetic diversity was observed on the basis of the percentage of polymorphic bands (99.91%), Shannon's information index (0.3592) and Nei's gene diversity (0.2085) at species level. Cluster analysis of UPGMA dendrogram, principal component analysis and Bayesian method analysis resolved these species in three different clusters, which was supported by morphological information. The Mantel test (r=0.4432) revealed a significant positive correlation between genetic and geographic distances. The collected data have an important implication in the identification, authentication, and conservation of the species of the genus Chlorophytum.

Heterochromatin distribution and comparative karyo-morphological studies in Vignaumbellata Thunberg, 1969 and V.aconitifolia Jacquin, 1969 (Fabaceae) accessions.

Chromosome studies along with heterochromatin distribution pattern analysis have been carried out in two domesticated species of Vigna Savi, 1824 which grow in contrasting geo-climatic conditions of India: Vignaumbellata Thunberg, 1969, a legume well acclimatized to subtropical hilly regions of North-east India and Vignaaconitifolia Jacquin, 1969, a species of arid and semi-arid regions in desert plains of Western India. Karyo-morphological studies in both species reveal 2n = 22 chromosomes without any evidence of numerical variation and the overall karyotype symmetry in chromosome morphology suggest that the diversification at intraspecific level in genus Vigna has occurred through structural alteration of chromosomes, rather than numerical changes. Heterochromatin distribution as revealed by fluorochrome binding pattern using CMA3 and DAPI, confirms the occurrence of relatively more GC content in Vignaaconitifolia as compared to Vignaumbellata. However, AT content was found to be comparatively higher in Vignaumbellata which perhaps play a role in species interrelationships.

Heterochromatin characterization through differential fluorophore binding pattern in some species of Vigna Savi.

Heterochromatin regions are the most intensively studied and best known chromosome markers in plants. In Vigna species, blocks of constitutive heterochromatin were found either in the terminal or interstitial region of the chromosomes. The number and distribution of CMA(+) and DAPI(+) binding sites exhibit high chromosomal variability with characteristic unique banding patterns in all the eight taxa. A predominant feature was observed, i.e., most of the CMA(+) binding sites were in the terminal region of the short arm of some chromosomes while DAPI(+) binding sites were found mostly in the intercalary region of the chromosomes. The higher divergence in the heterochromatin blocks, as revealed by chromomycin A3 (CMA) binding pattern, in a few taxa, viz. Vigna glabrescens, Vigna khandalensis, and Vigna mungo, suggests that the processes of divergent evolution of repetitive sequences in genomic DNA involve a guanine-cytosine (GC)-rich region. On the contrary, Vigna dalzelliana had shown a prominent adenine-thymine (AT)-rich repetitive DNA sequence in terminal regions in the short arm of chromosomes while Vigna umbellata had shown in interstitial regions. The presence of prominent heterochromatic-rich regions, either GC- or AT-rich regions, does facilitate the rate of chromosomal rearrangements leading to restructuring of the karyotypes and thereby helping the species to attempt structural alterations as means of speciation.

Phytochemical composition, antioxidant activity and HPLC profiles of Swertia species from Western Ghats.

Swertia chirayita is one of the potential medicinal plants of the family Gentianaceae in traditional medicine. Due to its high demand and scarcity, trade of chirayita is affected by adulterants. Swertia species from Western Ghats were compared with S. chirayita for phytochemical characterisation and antioxidant activities by using different extracts. This study revealed that acetone is the best extraction solvent of phenolic and flavonoid compounds with antioxidant properties as compared with other extracts. S. chirayita showed better antioxidant activity than other species with highest content of phenolics and flavonoids. Among the species from Western Ghats, Swertia minor has better antioxidant properties with higher content of phenolics and flavonoids when compared with S. chirayita. Gallic acid was detected in all species under study by using HPLC analysis. The Swertia species under study showed similar phytochemical properties and antioxidant potential and hence their use as substitute to S. chirayita needs to be further investigated.

Comparative analysis of heterochromatin distribution in wild and cultivated Abelmoschus species based on fluorescent staining methods.

A comparative analysis of fluorochrome-binding pattern in nine taxa of Abelmoschus had shown that the type, amount and distribution pattern of heterochromatin were characteristic for each taxa. The fluorescent chromosome-binding sites obtained by chromomycin A3 (CMA) and 4',6-diamidino-2-phenylindole (DAPI) staining in all the nine species showed constitutive heterochromatin CMA(+), DAPI(+) and CMA(+)/DAPI(+). Large amount of heterozygosity was observed with regard to heterochromatin distribution pattern in all the taxa studied. The CMA(+)-binding sites are comparatively less than DAPI(+)-binding sites which is clearly evident as AT-rich regions are more than GC-rich regions in all the nine taxa analysed in Abelmoschus. These CMA(+) and DAPI(+)-binding sites apparently rise with the increased in chromosome numbers of the different species. This pattern of heterochromatin heterogeneity seems to be a general characteristic feature. Therefore, the differential pattern of distribution of GC- and AT-rich sequences might have played an important role in diversification of the genus Abelmoschus. Polyploidy is an important factor in the evolution of Abelmoschus and the sole reason for range in chromosome numbers in this genus. It may be noted that, though often, but not always, the increase of DNA is caused by an increase in the amount of heterochromatin, i.e. increase of non-coding sections indicating restructuring of the heterochromatin. Thus, cumulative small and direct numerical changes might have played a role in the speciation of Abelmoschus.

Reconstructing the age and historical biogeography of the ancient flowering-plant family Hydatellaceae (Nymphaeales).

BACKGROUND: The aquatic flowering-plant family Hydatellaceae has a classic Gondwanan distribution, as it is found in Australia, India and New Zealand. To shed light on the biogeographic history of this apparently ancient branch of angiosperm phylogeny, we dated the family in the context of other seed-plant divergences, and evaluated its biogeography using parsimony and likelihood methods. We also explicitly tested the effect of different extinction rates on biogeographic inferences. RESULTS: We infer that the stem lineage of Hydatellaceae originated in the Lower Cretaceous; in contrast, its crown originated much more recently, in the early Miocene, with the bulk of its diversification after the onset of the Pliocene. Biogeographic reconstructions predict a mix of dispersal and vicariance events, but considerations of geological history preclude most vicariance events, besides a split at the root of the family between southern and northern clades. High extinction rates are plausible in the family, and when these are taken into account there is greater uncertainty in biogeographic inferences. CONCLUSIONS: A stem origin for Hydatellaceae in the Lower Cretaceous is consistent with the initial appearance of fossils attributed to its sister clade, the water lilies. In contrast, the crown clade is young, indicating that vicariant explanations for species outside Australia are improbable. Although long-distance dispersal is likely the primary driver of biogeographic distribution in Hydatellaceae, we infer that the recent drying out of central Australia divided the family into tropical vs. subtropical/temperate clades around the beginning of the Miocene.

Impact of spatial constraints during seed germination on the evolution of angiosperm cotyledons: a case study from tropical Hydatellaceae (Nymphaeales).

PREMISE OF THE STUDY: A bipolar embryo with cotyledons is a characteristic feature that appeared early in the evolution of seed plants. Cotyledon number is an important character in angiosperm classification. We explore the links between functional aspects of seed germination and the number and location of the cotyledons, using as a model the early-divergent angiosperm family Hydatellaceae, in which seedlings are superficially monocot-like. • METHODS: Seedlings of two species of tropical Hydatellaceae were studied using light and scanning electron microscopy. • KEY RESULTS: Seedlings of Trithuria cowieana bear two free cotyledons. Each cotyledon possesses a green, filiform, vascularized blade that resembles subsequent leaves, and a basal, nonvascularized, haustorial outgrowth that remains in close contact with the endosperm. Seedlings of Trithuria konkanensis have two free cotyledonary haustoria inserted close to each other and a leaf blade probably belonging to one of the cotyledons. The cotyledonary node elongates between the haustoria and the leaf blade to form a mesocotyl. • CONCLUSIONS: To date, the absence or presence of a cotyledonary tube represents the only known qualitative morphological difference between the two major clades of Hydatellaceae. Cotyledons with a haustorium and leaf blade are unusual at the scale of seed plants and probably evolved due to homeosis. The mesocotyl of T. konkanensis resembles that of grasses and sedges. Seedling diversity in Hydatellaceae and other seed plants is linked with the principal physical and spatial constraint of their embryo structure, with the primary root and shoot apical meristems located at opposite poles, and haustorial cotyledon tips.

Contrasting biogeographic and diversification patterns in two Mediterranean-type ecosystems.

The five Mediterranean regions of the world comprise almost 50,000 plant species (ca 20% of the known vascular plants) despite accounting for less than 5% of the world's land surface. The ecology and evolutionary history of two of these regions, the Cape Floristic Region and the Mediterranean Basin, have been extensively investigated, but there have been few studies aimed at understanding the historical relationships between them. Here, we examine the biogeographic and diversification processes that shaped the evolution of plant diversity in the Cape and the Mediterranean Basin using a large plastid data set for the geophyte family Hyacinthaceae (comprising ca. 25% of the total diversity of the group), a group found mainly throughout Africa and Eurasia. Hyacinthaceae is a predominant group in the Cape and the Mediterranean Basin both in terms of number of species and their morphological and ecological variability. Using state-of-the-art methods in biogeography and diversification, we found that the Old World members of the family originated in sub-Saharan Africa at the Paleocene-Eocene boundary and that the two Mediterranean regions both have high diversification rates, but contrasting biogeographic histories. While the Cape diversity has been greatly influenced by its relationship with sub-Saharan Africa throughout the history of the family, the Mediterranean Basin had no connection with the latter after the onset of the Mediterranean climate in the region and the aridification of the Sahara. The Mediterranean Basin subsequently contributed significantly to the diversity of neighbouring areas, especially Northern Europe and the Middle East, whereas the Cape can be seen as a biogeographical cul-de-sac, with only a few dispersals toward sub-Saharan Africa. The understanding of the evolutionary history of these two important repositories of biodiversity would benefit from the application of the framework developed here to other groups of plants present in the two regions.