3Asterids Very large, diverse group 10 orders, many families Apomorphies:iridoid compoundssympetalous corollaovules: one integument and the megasporangium is generally one cell thick
4Asteraceae Probably the most evolved of the families Two types of flowersRayDiskHerbs in our area, but can be trees in tropicsVery diverse: 19,000 species world-wideMany flowers on the head inflorescenceOld name is compositae – b/c a composite of flowers
5AsteraceaeInflorescence a head (capitulum): (usu.) many flowers arising from a compound receptacle, subtended by inflorescence bracts: involucral bracts or phyllaries, collectively termed the involucre.Calyx modified as pappus.Fruit an achene.
22Five types of heads: 1) discoid, with only disk flowers; 2) disciform, with central disk flowers and marginal, eligulate female flowers;3) radiate, with central (bisexual or male) disk flowers and peripheral (female or sterile) ray flowers;4) ligulate, with all ray flowers (typically with 5-toothed corolla apices);5) bilabiate, with all bilabiate flowers.
33AsteraceaeBecause the family is so large, it is divided into two Subfamilies which are then divided into tribes: 12 to 17 in the whole familyAster = Subfamily AsteroideaeSix tribes we’ll seeDandelion = Subfamily CichorioideaeOne tribe
34Tribes of the Aster Subfamily HeliantheaeAsteraeAnthemideaeSenecioneaeGnaphalieaeEupatorieaeCynareae
35Tribe Heliantheae – Sunflower tribe Opposite leavesVery resinousBracts attached to individual flowers (chaffy receptacle)Both types of flowersSunflower (Helianthus) and Echinacea
37Tribe Asterae – Aster Tribe No bracts at the bottom of individual flowersExample is genus Aster, generally fewer than 20 “petals” or ligulate flowersSimilar to above tribe, but without resin Chrysothamnus (Rabbitbrush or chico)Another important genus is Erigeron aka fleabane daisy
40Tribe Anthemideae – Chamomile Tribe Multiple layers of phyllaries of different lengthsRichly aromaticThin, dry, and translucent (i.e. scarious) bracts surrounding the flower baseArtemisia (sagebrush is in this tribe)Achillea, Chrysanthemum
41Involucre morphology one whorl two whorls many whorls Senecio vulgaris Coreopsis maritimaEncelia californica
53Tribe Cynareae or Cardueae (in your book) – Artichoke Tribe Head inside a cluster of tightly compressed bractsLike an artichoke, which is in this tribe, we eat the bracts!No ligulate flowersMany bristles on receptacle (spines inside artichoke)Many thistles are in this tribe, Cirsium and also knapweeds, CentaureaCynara is artichokeName for genus Carduus