Wisconsin flora “wordle” Poaceae - the grasses 321 279 • the second large independent shift to reduced flowers and spikelets for wind pollination • 4th largest family - 620 genera, 10,000 species • most important family (ethnobotanically) 283 1 2 grasses you collected! Picture key to grasses! Setaria spp. – Setaria spp. – foxtail foxtail Andropogon gerardii – Schizachyrium scoparium– Andropogon gerardii – Schizachyrium scoparium– big bluestem little bluestem big bluestem little bluestem Grasses of Iowa www.eeob.iastate.edu/research/iowagrasses Field Guide to Wisconsin Grasses – book in lab Sorghastrum nutans – Phalaris arundinacea – Bromus inermis– Indian grass reed canary grass smooth brome 3 4 1 Poales III: wind pollinated families Poales III: wind pollinated families • showy flowers, Evolutionary trends: • showy flowers, insect or bird insect or bird pollinated • nectar to pollen gathering to pollinated wind pollination • +/- reduced • reduced flowers - loss of • +/- reduced flowers, insect or perianth flowers, insect or wind pollinated wind pollinated • unisexuality sometimes • bracts become important • reduced • reduced flowers, wind • flowers to florets in spikelets flowers, wind pollinated pollinated 5 6 Poaceae - grasses Poaceae - grasses Poaceae related to more typical, although reduced, flowered Poaceae related to more typical, although reduced, flowered graminoid monocots with 6 tepals – Southern Hemisphere! graminoid monocots with 6 tepals – Southern Hemisphere! 7 8 2 Poaceae - grasses Poaceae - grasses Poaceae related to more typical, although reduced, flowered graminoid monocots with 6 tepals – Southern Hemisphere! What has driven this large and successful adaptive • bracted radiation? • 6 tepals 5076 species • mixed male & female 4 species 12 species flowers 12 species • achene female 5423 species male 9 10 Poaceae - grasses Poaceae - grasses node Vegetative features • first diversified ca. 70 mya in late • jointed, hollow, Cretaceous – tropical circular stems forest understories (culms) • major radiations • leaves 2-ranked or during formation of spiralled grasslands in mid Tertiary • blade, sheath, and ligule • shift to grasslands • intercalary basis for adaptive meristem above radiation? blade ligule nodes sheath Strömberg et al. PNAS 2005;102:11980-11984 11 12 3 Evolution of C4 Poaceae - grasses photosynthesis across angiosperms Adaptive features • intercalary Poaceae meristem - grazing & fire response • silica in stems • C4 photo- synthesis in arid “grasslands” • C4 photosynthesis evolved 62 times in angiosperms Nebraska grassland 25 mya 13 14 Poaceae - grasses Poaceae - grasses • has C4 photo- • has whole genome synthesis driven doubling been a key speciation? innovation for grass diversification? 5076 species 5076 species 4 species 4 species 12 species • C4 photosynthesis 12 species 12 species 12 species evolved 62 times in • WGD at base of angiosperms PACMAD and BOP clades 5423 species • 24 times just in 5423 species grasses • 11,000 vs. 28 spp. • all in PACMAD clade 15 16 4 Poaceae - grasses Poaceae - grasses The main unit of the Defining feature of inflorescence is the spikelet grasses are the which is composed of 2 glumes (spikelet bracts) and 1 spikelet and its florets or more florets Brome Oats spikelet glumes florets Dactylis glomerata Orchard grass 17 18 Poaceae - grasses Poaceae - grasses Each floret is surrounded by This spikelet with two glumes two floret bracts - the outer has two florets each with two lemma and the inner palea floret bracts - the outer lemma (usually not seen until and the inner palea anthesis - when florets open) Brome Oats glumes lemma lemma palea palea Dactylis glomerata Orchard grass 19 20 5 Poaceae - grasses Poaceae - grasses Although considerable variation occurs in florets (among species or within a spikelet), most of our species have the following floret anthesis – expose structure: anthers & styles fungal endophytes – preventing spores • Perianth represented by 2 lodicules entering fruit? What is function of lodicules? What is function of lodicules? 21 22 Poaceae - grasses Poaceae - grasses • fungal endophytes • fungal endophytes (ascomycetes) produce (ascomycetes) produce physiologically active physiologically active alkaloids alkaloids • anti-herbivory defense against grazing mammals (defensive mutualism)? Nebraska grassland 25 mya Nebraska grassland 25 mya 23 24 6 Poaceae - grasses Poaceae - grasses Although considerable variation occurs in florets (among species or within a spikelet), most of our species have the following floret structure: bisexual floret • phylogenetic analysis of bamboos turned out to be phylogeny of endophytic fungi! • Perianth represented by 2 lodicules • Stamens 3 • Superior gynoecium of 2 fused carpels Lynn Clark • One ovuled fruits called a grain or caryopsis = seed fused to ovary wall What parts homologous to other flowers? Jonathan Wendel 25 26 Poaceae - grasses Poaceae - grasses Although considerable variation occurs in florets (among species • lodicules = petals or within a spikelet), most of our • palea/lemma = sepals species have the following floret structure: Toby Kellogg – Missouri Bot Gard • Perianth represented by 2 lodicules • Stamens 3 • Superior gynoecium of 2 fused carpels • One ovuled fruits called a grain or caryopsis = seed fused to ovary wall What parts homologous to other flowers? What parts homologous to other flowers? 27 28 7 Poaceae - grasses Poaceae - grasses South American origin! BOP Grass phylogenetics PACMAD Basal grasses 29 30 Poaceae - grasses Poaceae - grasses Anomochloa marantoidea Streptochaete 4 stamens! Subfamily Anomochlooideae (no spikelets, lodicules) 31 32 8 Poaceae - grasses Poaceae - grasses Subfamily Pharoideae (herbaceous bamboos) Grass phylogenetics Pharus Core grasses 33 34 Poaceae - grasses Poaceae - grasses Bambusa Subfamily Ehrhartoideae (stamens 6, but 2 styles) Subfamily Bambusoideae Oryza sativa - rice (6 stamens, 3 lodicules, 3 stigmas) 2nd most important crop plant in the world Ochlandra 35 36 9 Poaceae - grasses Poaceae - grasses Subfamily Ehrhartoideae Poa annua - bluegrass (stamens 6, but 2 styles) Subfamily Pooideae Ziziana aquatica - wild rice (Spikelets with more than one grain forming floret; Important native American food; Lemma with 5 nerves) unisexual spikelets Poa pratensis - Kentucky bluegrass 37 38 Poaceae - grasses Poaceae - grasses Dactylis glomerata - orchard grass Elymus hystrix bottlebrush Bromus inermis - bromegrass Avena sativa - oats 39 40 10 Poaceae - grasses Poaceae - grasses Subfamily Arundinoideae (large inflorescences) Phalaris arundinacea Reed canary grass Calamagrostis canadensis - bluejoint grass Phragmites australis - common reed Circumboreal species; non- native populations have become invasive and displaced native populations 41 42 Poaceae - grasses Poaceae - grasses Subfamily Chloridoideae (Spikelets arranged often one-sided) Spartina pectinata Prairie cord grass Cortaderia - plume grasses from Bouteloua curtipendula pampas Sideoats grass 43 44 11 Poaceae - grasses Poaceae - grasses Subfamily Panicoideae (2 florets, bottom reduced, sterile) Digitaria - crabgrass Panicum virgatum - switchgrass Dichanthelium sp. - panic grass Setaria - foxtail 45 46 Poaceae - grasses Poaceae - grasses Andropogon gerardii - big bluestem Saccharum - Sorghum - sugarcane sorghum 47 48 12 Poaceae - grasses Poaceae - grasses The origin of maize from teosinte wild relatives in Mexico involved few genes Female spikelets condensed into Male spikelets in cob or spike panicle or tassel Zea mays - maize Tripsacum - teosinte John Doebley Zea mays - maize 49 50 13.