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Home , Hypanthium, Umbel

BIOL 317: Identification and Classification Summer 2015 - Notes

Week 2 – Tuesday Understanding phylogenies (cont.) • Different kinds of groups • Monophyletic group = clade • includes ancestor and all descendents • characterized by synapomorphies – shared derived traits – evolved in common ancestor of group and is found in all descendents • only kind of group that should be named in phylogenetic classification § gives classification scheme predictive power – all members of named groups have closest relatives within group • examples: , tracheophytes, • Paraphyletic group • includes ancestor and some descendents • characterized by symplesiomorphy – shared ancestral traits – evolved in common ancestor of group but was lost or changed in some descendents • example: (symplesiomorphy: non-vascular condition) • Polyphyletic group • includes multiple lineages without their common ancestor • characterized by homoplasies (analogies/convergences) – traits that evolved independently in multiple lineages • example: group combining land and fungi (homoplasy: sessile terrestrial lifestyle) • Polarity – direction of evolutionary change • outgroup comparison • some terms: § ingroup – taxon of interest § outgroup – taxon outside of ingroup but closely related; ideally the sister group to the ingroup • character state found in outgroup is assumed to be ancestral state; alternative state is derived (change is from ancestral to derived state) • other methods of determining polarity • using fossil record – older fossils have ancestral state • assume states changed from simple to complex • assume the more common state is ancestral • look for correlations between character states • Converting phylogenetic to phylogenetic classification scheme • only monophyletic groups should be named • not all monophyletic groups have to be named • rank of named taxon is arbitrary • different ranks within a group are different in relative inclusiveness, but the same rank in different groups are not necessarily equivalent • ranks do not correlate with a specific amount of species diversity, morphological diversity, age, etc. – the form and structure of plants • Vegetative morphology – parts of plants involved in growth, development, , support • 2 organ systems and 3 organs, which differ in anatomy and development • system – usually belowground • – involved in water and mineral update, anchorage § taproot – one main root with smaller lateral roots § fibrous – main root and many lateral roots of roughly equal size § adventitious – roots that develop from system § modifications: • form symbioses with soil microbes – eg. root nodules housing N-fixing bacteria • food storage – eg. • support – eg. adventitious roots on • Shoot system – usually aboveground • stems – involved in vertical growth, support § node – part of stem where is attached § internode – part of stem between nodes § modifications: • stolon – horizontally growing stem aboveground for vegetative propagation • – horizontally growing stem underground for vegetative propagation; sometimes thickened for food storage • – short shoot with thickened for food storage • – vertically compressed and thickened stem for food storage • tuber – section of rhizome thickened for food storage • cladode - flattened stem for photosynthesis • thorn - sharpened shoot for protection • leaves – involved in photosynthesis § always associated with an axillary § parts of leaf • blade – broad flattened area for photosynthesis • – slender stalk that attaches blade to stem (leaves without petioles are sessile) • stipule – paired, usually blade-like structure at base of leaf; in some, not all, leaves • veins - usually there is a central, more prominent vein called the midvein or midrib § leaf types: • simple - blade undivided • palmately compound - blade divided into leaflets, which all come off one central point • pinnately compound - blade divided into leaflets, which come off central axis • ternately compound - blade divided into three leaflets (also called trifoliate) § leaf arrangement/phyllotaxy: • alternate - one leaf per node • opposite - two leaves per node • whorled - three or more leaves per node • basal - leaves tightly grouped together at base of plant; arrangement is actually one of the three above, but internodes are too short to allow us to tell; eg. dandelion § leaf venation: • primary veins - palmate - pinnate - parallel • smallest veins - reticulate/net-veined - parallel § shape of leaf includes the overall shape, leaf tip, leaf base, and leaf margin (see Vegetative Morphology lab handout) § modifications: • colored for attraction • bud scales - small, hardened leaves for protection of • spines - sharpened leaves for protection • bud – embryonic shoot system, with its own developing stem, leaves, and buds § apical/terminal – at tip of shoot; continues to elongate shoot § axillary/lateral – in axil between top of leaf and stem; grows into lateral/side shoot • fun note: sharpened projections from the are called prickles; e.g. "thorns"

Week 2 – Thursday Plant morphology (cont.) • Reproductive morphology – parts of plants involved in sexual reproduction • - compressed shoot, usually with four whorls of modified leaves • idea that the parts of flower are modified leaves was first articulated by Johann Wolfgang von Goethe (1749-1832), German writer and scientist • four whorls of flower, from outside to inside, or bottom to top: § (collectively, the calyx) - usually greenish, protect inner whorls when flower is in bud § (collectively, the corolla) - usually colorful, attract • - collective term for both the calyx and corolla • - term used for perianth organs when outer two whorls look alike § (collectively, the androecium) - serve male function • anther - broad sac-like structure producing inside • filament - stalk connecting anther to point of attachment § pistils (collectively, the ) - serve female function • - tip of pistil that is receptive to pollen • style - stalk connecting stigma to • ovary - broader structure containing / • other parts of flower: § - stem leading to flower, when flower is solitary § - stem leading to flower, when flower is part of • in this case, the peduncle is the stem leading to the inflorescence § - end of stem where whorls of flower are attached • some terms for : § complete - has all four whorls § incomplete - is missing one or more whorls § perfect - has both stamens and pistils § imperfect - is missing stamens and/or pistils • staminate - is missing pistils • pistillate - is missing stamens • some terms for species with imperfect flowers - monoecious - both staminate and pistillate flowers on same individual plant - dioecious - staminate and pistillate flowers on separate plants • floral symmetry § radial - has multiple planes of symmetry • flower with radial symmetry is actinomorphic or regular § bitlateral - has one plane of symmetry • flower with bilateral symmetry is zygomorphic or irregular

• fusion of organs § connate - when organs of same are fused to each other • gamopetalous/sympetalous - flower with connate petals • polypetalous - flower with free petals § adnate - when organs of one whorl are fused to those of another • epipetalous stamens - stamens are fused to petals § pistils vs. carpels • pistil - distinct structure with its own ovary, style, stigma • carpel - subunit of pistil • simple pistil - equivalent to single free carpel - there may be one or more per flower • compound pistil - composed of multiple fused carpels - there can only be one per flower - is evidenced by multiple stigma lobes, multiple styles, and/or multiple chambers in ovary • ovary position § superior - ovary is above where other whorls of flower are attached • flower is hypogynous if other whorls are directly attached below ovary • flower is perigynous if other whorls are attached to a cup-like structure () which is attached below ovary § inferior - ovary is below where other whorls of flower are attached • flower is epigynous • placentation - where ovules are attached inside ovary § some terms for structures: • septum - wall of dividing ovary crosswise • locule/cell - chamber or section inside ovary; there may be only one if ovary if undivided (no septum) or more if divided • placenta - tissue where ovules are attached § marginal - in simple pistil, ovules are attached to one side of ovary wall § parietal - in compound pistil, ovules are attached to multiple sides of ovary wall § axile - in divided ovary, ovules are attached to central part of septum § free-central - in undivided ovary, ovules are attached to central § basal - ovules are attached to base of ovary • Inflorecence - structure made of multiple flowers • determinate - inflorescence shoot ends in flower which is produced first, additional flowers are produced on lateral ; usually center or upper- most flower opens first § cyme - determinate inflorescence • indeterminate - inflorescence shoot continues to grow, flowers are produced on lateral shoots; usually outer or lower-most flower opens first § spike - flowers lacking pedicels (sessile) on elongate shoot § head - flowers lacking pedicels on compressed shoot § - pedicellate flowers on elongate shoot § panicle - compound inflorescence, i.e. raceme of § corymb - flat-topped inflorescence in which pedicels attach at different points along inflorescence shoot; pedicels differ in length to reach same level § - flat-topped inflorescence in which pedicels attach at same point at tip of inflorescence shoot; pedicels roughly equal in length • - mature ovary containing seeds • fleshy - at least part of ovary wall becomes fleshy; animal-dispersed § - ovary wall is roughly homogenous in texture; usually many seeds per fruit; eg. kiwi § drupe - ovary wall has outer fleshy layer and inner hard, stony layer; one per fruit; eg. • dry - ovary wall becomes dry; may be dispersed in various ways § indehiscent - ovary wall does not split open; seeds are not released from inside ovary - - one-seeded with no special modifications to ovary wall - samara - one-seeded with enlarged wing on ovary wall for - dispersal § dehiscent - ovary wall splits open to release seeds - follicle - from simple pistil - - from compound pistil • when several separate ovaries combine to form fruit structure § multiple - ovaries from multiple flowers combine; eg. pineapple § aggregate - ovaries from single flower combine; eg. blackberry • Seed - mature containing • cotyledon - first leaf or leaves of embryo, often thickened to provide food for embryo after ; also called seed leaves • radicle - young root of embryo • plumule - young shoot of embryo • seed coat - layer of tissue surrounding embryo, comes from integument (see notes below)

Plant life cycle • alternation of generations – plants alternate between multicellular diploid and multicellutlar haploid generations • some terms: • haploid - having one set of chromosomes (a set can consist of any number of chromosomes; eg. in humans, a set consists of 23 chromosomes so a haploid cell has one set, or 23 chromosomes) • diploid - having two sets of chromosomes, one set from each of two parents (eg. in humans, a diploid cell has two sets, or 46 chromosomes) • mitosis - type of cell division where daughter cells have same ploidy level as mother cell • meiosis - type of cell division where the ploidy level of daughter cells is reduced by half • fertilization - fusion of haploid sperm and egg to produce diploid zygote • - multicellular diploid generation, produces via meiosis • - multicellular haploid generation, produces gametes via mitosis • - unicellular haploid cell which will divide to become gametophyte • gamete - sperm and egg; unicellular haploid cells which will fuse to become zygote • zygote - diploid cell formed by fusion of sperm and egg • embryo - young sporophyte • variations in land plant life cycle • bryophytes • gametophyte - dominant; larger, free-living, long-lived • sporophyte - smaller, dependent, short-lived • seedless vascular plants (lycophytes, monilophytes) • gametophyte - smaller, free-living, short-lived • sporophyte - dominant; larger, free-living, long-lived • spermatophytes • gametophyte - much smaller, dependent (contained entirely within sporophyte), short-lived § pollen grain - male gametophyte within sporopollenin wall; consists of only two or three cells, some of which are sperm cells § ovule - female gametophyte within integument (protective tissue layer); gametophyte consists of fewer than ten to several hundred cells, some of which are egg cells • sporophyte - dominant; larger, free living, long-lived • must precede fertilization § pollination - transfer of pollen grain (from the anther in angiosperms) to receptive surface of female structure on sporophyte (in angiosperms, the stigma of the pistil); after pollination, the male gametophyte will grow out of the pollen grain and toward the ovule § fertilization - fusion of sperm and egg to produce zygote

Angiosperm innovations • flower - compressed shoot, usually with four whorls of modified leaves specialized for sexual reproduction • pistil - ovary encloses and protects ovules • embryo sac - reduced female gametophyte, usually consists of only seven cells with eight nuclei, one of which is the egg cell • - triploid tissue that develops from fusion of sperm with central cell (cell in embryo sac with two nuclei, called polar nuclei); provides nutrition to developing embryo • - two fusion events involving sperm occur in angiosperms; male gametophyte produces two sperm cells § fusion of sperm and egg produces zygote (embryo) § fusion of sperm and central cell produces endosperm • bitegmic ovule - two layers of integuments (protective tissue) surround embryo sac • sieve tube cells (phloem) and vessel elements (xylem) - derived cell types provide more efficient transfer of food (phloem) and water (xylem) through plant body