Diversity and Evolutionof Asterids. . . dogwoods, blueberries, andprimroses . . .Asterids• continue survey through the eudicotsor tricolpates after completing Rosids• the Asterids are the second of the twolarge groups of dicots and the easier oneto define morphologicallyrosidasteridAsterid Characteristics• fused petals - sympetaly• stamen number < petal number• stamens fused to corolla tubeAsterid Characteristics• iridoid compounds (with losses)Picrorhiza kurroaGardenia• ‘basal asterids’ have them (previously not placed withasterids)Rubiaceaecoffee familyScrophulariaceaesnapdragon familyAsterid Characteristics• one layer of integuments in ovule vs. two in other groupsbitegminae• the “unitegminae” (vs. bitegminae) of van Tieghem in1901 = new Asterid group!Asterid Composition• composition of Asterids is largelycongruent with previous morphologyAsterid Composition• exceptions include the ‘basal asterids’and separate petal or small flower ordersApiaceae - carrot familyAquifoliaceae - holly familyAsterid Composition• exceptions include the ‘basal asterids’and separate petal or small flower orders• some of these “non” sympetalousAsterids (e.g., order Cornales) have“early” petal ring primordia indevelopment• subsequent petal development isseparate, so appear to be polypetalousEarly ring primordia of 5 petals insnapdragon (a true asterid) [EMBO Journal (2003)22: 1058–1066]Basal Asterids• basal asterids represent a gradetowards the core asterids• the “standard” Asterid flower has notbeen fixed• great variation in floral form in the twoorders Cornales and EricalesCornus ChimaphilaCornales• order sister to remainder of Asterids,comprises 7 small families (diverse)Cornaceae LoasaceaeNyssaceaeHydrangeaceae*Cornaceae - dogwoods• mainly north temperate shrub family of 2 genera and 85 speciesAlangiumCornus*Cornaceae - dogwoods• opposite, simple leaves• arcuate venation*Cornaceae - dogwoodsCA 4 CO 4 A 4 G (2) __• 4 merous, small flowers withseparate petals• 2 carpellate inferior ovary• fruit a 2-seeded ‘drupe’bracts• some inflorescences surroundedby showy bracts• “head” or “pseudanthium” (falseflower)Cornus stolonifera - red osier*Cornaceae - dogwoodsEastern North Americansmall tree with 4conspicuous white bractsCornus florida - flowering dogwood*Cornaceae - dogwoodsLow to ground borealsubshrub, appears to have awhorl of leaves, and has 4showy bracts below flowersCornus canadensis - bunch berry*Cornaceae - dogwoodsCommon in wet places,distinctive with red stemsCommon component ofshrub carrCornus racemosaGray dogwoodCornus stoloniferaRed-osierNyssa sylvatica - sour gum, blackgum, black tupelo• rare, flowers unisexualwith male flowers inumbels; drupes blackNyssaceae - black gumsClosely related to dogwood family, small familyof trees and shrubs from North Temperate regionHydrangeaceae - hydrangeasPhiladelphus -mock orangeHydrangea arborescensAnother small family of trees, shrubs, and vines from NorthTemperate region - many ornamental woody plants• most recently placed inSaxifragaceaeHydrangeaLoasaceae – evening starsMentzelia crocea – Sierra blazing starAnother small family related to hydrangeas but largelyrestricted to the New World• rosid-like flowers• parietal placentation• many twining with irritantsEricales• large, important order of 23 families, >11,000species• will focus on just a few families and learnEricaceae (blueberries) and Primulaceae(primroses)blueberry primroseEricales• Ericales represent less than 6% of eudicot diversity, and 1/3of these belong to Ericaceae alone . . . but• 10% of the understory species in tropical rainforests• and about 22% of the total stems in these forestsClavijaEricales• Ericales exhibit great diversity in habit and nutrient uptakestrategies• mycorrhizal associations• mycorrhizal parasites (mycotrophs)Monotropa -Indian pipe Arctostaphylos - bearberryEricales• Ericales exhibit great diversity in habit and nutrient uptakestrategies• parasitism• carnivoryMitrastema -parasite Sarracenia - pitcher plantEricales• as early diverging Asterids, Ericalesexhibit a bewildering mixture of Rosidand Asterid featuresRosid core AsteridCorolla Structuresympetaly polypetalyfor instance in …FouquieriaceaePrimulaceaeLecythidaceaeRoridulaceaeFouquieria CouroupitaCorolla StructureRe-examined in light ofDNA based relationships• corolla evolution is stillcomplicated• perhaps one or twoseparate origins ofsympetaly and two or threereversals to choripetalySchoenenberger, Anderson,Sytsma 2005Integument Numberunitegmic bitegmicfor instance in …ClethraceaeSymplocaceaeTheophrastaceaeMarcgraviaceaeClethra JacquiniaIntegument NumberRe-examined in light ofDNA based relationships• ovule integument evolutionis still complicated• multiple swtiches from thederived asterid condition ofunitegmic to bitegmic andback againSchoenenberger, Anderson,Sytsma 2005Stamen Number1 whorl 2+ whorlsfor instance in …PolemoniaceaeRoridulaceaeTheaceaeActinidiaceaeSchimaShortiaTheaceae - tea, camelliaNorth Temperate family of evergreen, serrate leaved shrubs (7genera and up to 400 species)Schima• flowers have separate petalsand many stamensCamelliasinensis - teaTheaceae - tea, camelliaStewartia sinensisStewartia malacodendronStewartia pseudocamelliaEastern North Americaand Eastern Asia is the“classic” northtemperate disjunctionpattern*Ericaceae - blueberriesWorldwide woody family, exceptlowland tropics, of 126 generaand nearly 4,000 species• the E. Asian genus Enkianthusis sister to the rest of the familyEnkianthus*Ericaceae - blueberries• comprises the former familiesPyrolaceae, Monotropaceae,Empetraceae, EpacridaceaeMonesesEpacrisMonotropaEmpetrum*Ericaceae - blueberries• characteristic of nutrient poor soils - bogs, acidic pine dominatedforests, tropical epiphytes, or sandy soils• mycorrhizal relationship, forming haustoria - root to fungusconnection, permits nutrient uptake by plants, carbon uptake byfungusLeatherleaf in bog Cavendisia - cloud forest epiphyte*Ericaceae - blueberriesMonotropa hypopithysPinesapMonotropa unifloraIndian-pipePterospora andromedeaGiant pinedrops• mycotrophs - lacking chlorophyll and totally parasitizing thefungus for food, nutrients, and water• former family Monotropaceae, derived from within mycorrhizalEricaceae*Ericaceae - blueberriesLedumLabrador teaNote revolute