BIOL 317: Plant Identification and Classification Summer 2015 - Notes Week 7 – Tuesday Core Asterids comprises two large clades, the campanulids and the lamiids commonly shared traits: • 5-merous flower • gamopetalous corolla • 5 stamens in a single whorl, alternate with petal lobes • epipetalous stamens • 2 fused carpels Campanulids typically have inferior ovary Dipsacales another important family is Adoxaceae (elderberry, viburnum) Caprifoliaceae (honeysuckle family) 42 genera, 890 spp. distributed widely, but especially diverse in northern temperate zone herbaceous or woody (shrubs or vines) leaves - simple or compound; opposite flowers • zygomorphic, some weakly so • sepals 5, fused • petals 5, fused . often bilabiate, with 2 upper petal lobes and 3 lower petal lobes (notable exception is Lonicera [honeysuckle] which has 4 upper petal lobes and 1 lower petal lobe) • stamens 4 or 5, epipetalous • pistil compound (2-5 carpels); ovary inferior . usually 1 ovule/carpel; in some species, only 1 carpel matures • fruit: capsule, achene, berry, or drupe Older circumscriptions of Caprifoliaceae were paraphyletic with respect to Adoxaceae, Dipsacaceae, and Valerianaceae, families with mostly herbaceous members. In order to make monophyletic families, Sambucus and Viburnum were transferred to Adoxaceae, which all have actinomorphic flowers. Dipsacaceae and Valerianaceae were sunk into Caprifoliaceae in the classification followed here. Other phylogenetic classifications maintain Dipsacaceae and Valerianaceae, define Caprifoliaceae as a narrower clade, and erect new families Linnaeaceae, Diervillaceae, etc. includes PNW shrubs and wildflowers (Lonicera ciliosa - orange honeysuckle, Symphoricarpos albus - snowberry, Linnaea borealis - twinflower, Valeriana sitchensis - Sitka valerian, etc.), weeds (Dipsacus fullonum - teasel, etc.), and ornamentals (Weigela sp., Abelia sp., Lonicera japonica - Japanese honeysuckle, Centranthus ruber - red valerian, Scabiosa columbaria - pincushion flower, etc.) Apiales another important family is Araliaceae (ginseng, English-ivy) Apiaceae (carrot family) 484 genera, 3780 spp. distributed worldwide, but especially diverse in northern temperate zone herbaceous leaves - often compound, some simple; alternate; sheathing base often aromatic - possess ethereal oils, terpenoids, and other volatile chemicals used for herbivore defense inflorescence - umbel (pedicels originate from single point and flowers produced at about the same level); many with compound umbels flowers • actinomorphic or zygomorphic • sepals 5 • petals 5, free - secondary loss of fusion • stamens 5 • pistil compound (2 carpels); ovary inferior . 1 ovule/carpel . stylopodium - swollen style base secretes nectar • fruit: schizocarp includes PNW wildflowers (Lomatium spp. - desert-parsley, Sanicula spp. - sanicle, Heracleum maximum - cow-parsnip, Angelica spp., etc.), weeds (Conium maculatum - poison-hemlock, etc.), food crops, herbs, and spices (Daucus carota - carrot, Pastinaca sativa - parsnip, Apium graveolens - celery, Foeniculum vulgare - fennel, Petroselinum crispum - parsley, Coriandrum sativum - cilantro, coriander, Pimpinella anisum - anise, Cuminum cyminum - cumin, Carum carvi - caraway, etc.), and ornamentals (Eryngium amethistium - sea holly, etc.) Asterales often have secondary pollen presentation (also called plunger or brush pollination, or a pollen pump) • Anthers of stamens form tube through which style and stigma grow. Pollen is deposited on outside of immature stigma lobes, where it is presented to pollinators. Later, the stigma lobes mature and open to expose the inner receptive surface. Campanulaceae (bellflower family) 84 genera, 2380 spp. distributed worldwide most herbaceous, some woody (shrubs) leaves - simple; alternate milky latex flowers • actinomorphic (subfamily Campanuloideae) or zygomorphic (subfamily Lobelioideae) • sepals 5, fused • petals 5, fused . bell- or tube-shaped (subfamily Campanuloideae) . 2- or 1-lipped (subfamily Lobelioideae) • stamens 5 . secondary pollen presentation - anthers fused or held together to form tube around pistil • pistil compound (2-5 carpels); ovary inferior • fruit: capsule or berry includes PNW wildflowers (Campanula spp. - bellflower, Downingia spp., etc.) and ornamentals (Campanula spp., Lobelia spp., etc.) Asteraceae/Compositae (sunflower family) 1620 genera, 23600 spp. - among the two largest families of angiosperms distributed worldwide herbaceous or woody (shrubs or trees) leaves - usually simple, but can be highly dissected; variously arranged inflorescence - head (capitulum) - sessile flowers densely clustered • subtended by whorl (involucre) of bracts (phyllaries) • discoid head - have only disk florets • ligulate head - have only ligulate florets • radiate head - have ray florets at margin, disk florets in center flowers • actinomorphic (disk floret) or zygomorphic (ray or ligulate floret) • flowers sometimes individually subtended by bracts on the receptacle (chaff) • sepals none, or 2-many . if present, then highly modified into scales or bristles (pappus) • petals 5, fused . tube-shaped (disk floret) . form ligule - expanded single lobe (ray or ligulate floret) • stamens 5, epipetalous . secondary pollen presentation - anthers fused together to form tube around pistil • pistil compound (2 carpels); ovary inferior . 1 ovule/carpel, but only 1 carpel matures • fruit: achene (cypsela) includes PNW shrubs and wildflowers (Artemisia tridentata - big sagebrush, Cirsium spp. - thistle, Balsamorhiza sagitata - arrowleaf balsamroot, Arnica spp., Erigeron spp. - fleabane, etc.), weeds (Taraxacum officinale - dandelion, Centaurea spp. - knapweed, etc.), food crops (Lactuca sativa - lettuce, Cynara cardunculus - artichoke, Helianthus annuus - sunflower), and ornamentals (Chrysanthemum spp., Zinnia spp., Tagetes spp. - marigold, etc.) Plant Speciation Species concepts - what is a species? • are species real units that exist in nature, or are they human constructs used to simplify, organize, and understand nature? • what concepts are used to define and delimit species? . typological - a perfect form exists for each species, and any variation is the result of unimportant environmental imperfections - prevailing concept from ancient Greeks (Plato, Aristotle) to Linnaeus . morphological - variation in morphology is important and should be measured, and species boundaries are defined by gaps or discontinuities in morphology - rose in prominence after Darwin . biological - species boundaries are defined by reproductive isolation - advocated by Ernst Mayr (1940's) . mate-recognition - species defined by mating specificity and share common mating/fertilization system . phylogenetic - species are monophyletic groups that share derived traits (synapomorphies) • Most concepts revolve around the idea that species are unique evolutionary lineages, but differ in how lineages are determined to be divergent enough from others to warrant being called a new species. Given the diversity of life- histories and evolutionary histories found across the tree of life, it is unlikely that any one species concept will be suitable and applicable to all organisms. Week 7 – Thursday Plant Speciation (cont.) Speciation - how do new species form? • new species are derived from previously existing species • new species begin to form when a population becomes isolated from its parent population, so that the exchange of genetic material (gene flow) ceases • Allopatry - geographic separation . most speciation events are believed to have begun when populations became geographically isolated . while geographically isolated, populations may accumulate genetic differences due to: selection - different environments in different areas may select for different beneficial mutations in the different populations drift - different mutations may become prevalent in different populations by random chance . if populations later meet, they may: hybridize - genetic differences do not affect the ability of populations to successfully mate, and the populations merge and remain a single species be genetically incompatible - genetic differences cause hybrid offspring to be inviable, infertile, or unfit - in this case, developing mating barriers becomes adaptive and may be selected for (reinforcement), so individuals do not waste resources on mating events that produce unfit offspring have mating barriers - genetic differences result in morphological/developmental/behavioral differences that prevent individuals from different populations from mating . mating barriers temporal - differences in timing of reproduction, during the course of the day (diurnal) or year (seasonal) habitat - differences in habitat preference may lead to fine-scale geographic separation floral - differences in morphology of the flower - may attract different pollinators - structural differences may result in interactions with the pollinator in different ways, e.g. deposit pollen on different areas of the pollinator's body • Other modes of speciation (especially common in plants) . Hybridization - hybrid offspring may persist but be unable to mate with either parent species, thus forming a new species hybrid offspring are often sterile due to chromosomal incompatibilities between parental genomes, but hybrid plants may persist by asexual reproduction . Polyploidization - increase in the number of sets of chromosomes, e.g. from diploid (2 sets) to tetraploid (4 sets) may result in instantaneous