4/13/18 Week 3; Monday BRING TEXTBOOK TO CLASS Announcements: Quiz on Wednesday Arb field trip on Th 10:30 AM and 2:30 PM, Fri 10:30 AM, Sat 10:30 AM; sign up in lab - directions to Arb are on class website (bus routes 43 or 48) Today we start to learn families; there will be 42 required families (33 in lecture plus 9 in labs only). Props: Magnolia flower; Laurus nobilis or Umbellularia leaves Early Angiosperm flowers. While we don’t know with any certainty what the earliest angiosperm flowers looked like, we can infer from the flowers of surviving early lineages what traits they shared. Ancestral condition Derived condition 1) Insect pollinated wind, bird, water, etc. 2) Radial symmetry bilateral symmetry 3) Perfect (both male and female parts in each flower; plants hermaphroditic) unisexual (mono- ,dioecious) 4) Perianth parts - sepals and petals undifferentiated distinct calyx & corolla - several to many; indeterminate number few in set number (e.g., 3 or 5) - spirally arranged arranged in whorls - distinct (not fused to each other) fused to each other 5) Laminar stamens distinct filament & anther 6) Monocolpate pollen tricolpate pollen 7) Pistils simple pistils compound 8) Superior ovaries inferior ovaries Magnoliales and “Basal Tricolpates” Those families that might justifiably be called “basal angiosperms” are characterized by monosulcate pollen and two cotyledons. The Textbook has more information on each family; I’ll just hit the highlights NOTE 1: TO USERS OF JUDD ET AL., 3RD ED: SOME FAMILY CIRCUMSCRIPTIONS HAVE CHANGED IN 4TH EDITION NOTE 2: WE DON’T COVER THE FAMILIES IN THE SAME ORDER AS THE TEXT Page 24 4/13/18 Magnoliales Magnoliaceae (2 gen/220 spp) – Magnolia family 1) woody trees or shrubs; may be evergreen or deciduous 2) ethereal (aromatic) oils – ‘primitive’ smell when leaves are crushed 3) simple leaves with pinnate venation and entire margin 4) large showy flowers DEMO – Magnolia flower - always bisexual (plants hermaphroditic) - floral parts borne on elongate receptacle - many parts, spirally arranged; - sepals and petals poorly differentiated - laminar stamens poorly differentiated into anther and filament - ovary superior - fruit usually a follicle (often many aggregated together) or samara - follicle - 1-carpellate fruit that dehisces on one side (Magnolia sensu lato) - samara - 1-carpellate winged, indehiscent fruit (Liriodendron) - floral formula: * ∞, ∞, ∞, ∞ follicle, samara Floral Formulas - shorthand notation to describe the structure of a flower X or *, Ca, Co, A, G, fruit type Rose: * 5, 5, ∞, ∞ , aggregate achene specifically ‘rose hip’ tomato: * 5,5,5,2 berry Laurales - another group of primitive woody dicots Lauraceae - most well-known family of Laurales (very diverse in tropics) (50 gen/2500 spp) – Laurel family -- FAMILY NOT COVERED IN LECTURE known for ethereal oils DEMO – Laurus leaves includes: Laurus nobilis - Bay; Cinnamomum zeylandica - cinnamon; C. camphora - camphor; Persea americana – avocado; Umbellularia californica – California bay Laurel Page 25 4/13/18 “Basal Tricolpates” (‘basal eudicots’) these plants have tricolpate pollen, thereby placing them firmly with the other ‘higher’ dicots we call Tricolpates (or Eudicots) Ranunculaceae (47 gen/2000 spp) Buttercup family This family is difficult to characterize, because of tremendous variation, but there usually is little difficulty recognizing it because of a combination of characters 1) usually herbs; some vines or shrubs 2) leaves usually simple; sometimes deeply lobed or compound 3) flowers highly variable - usually hermaphroditic (with bisexual flowers), some dioecious (with unisexual flowers) - usually radially symmetrical, - sometimes bilaterally symmetrical - parts spirally arranged or in whorls (then in 5s) - petals and sepals both showy or petals reduced/missing; petals often with nectary - ovary always superior - Stamens numerous, spirally arranged - carpels usually numerous and separate, but sometimes only one - fruit a follicle, achene, or berry - berry - 1 or more carpels, fleshy - achene - 1-carpellate indehiscent fruit floral formula: *(X) 5(-∞), 5(-∞), 5(-∞), 5(1-∞) follicle, achenes, berry Berberidaceae (15 gen/650 spp) Barberry family 1) perennial herbs or shrubs (secondarily woody) 2) lvs. simple or compound 3) fl parts in whorls of 3, or occasionally in 4 - sepals and petals usually 6 each and similar - stamens usually 6 (but may be 4 or many) with valvate anthers ‘flaps’ on anthers flip up when mature to release pollen sensitive area in filament near base causes stamen to move toward gynoecium - single carpel; stigma often with 3 lobes (sometimes interpreted as a 3 fused carpels); parietal or basal placentation; - fruit usually a berry; sometimes a follicle. floral formula: * 6, 6, 4-18, 1 (3) berry, follicle [carpels fused] Page 26 4/13/18 Week 3; Wednesday Props: lvs of Betula or Corylus; Quercus inflorescences; Alnus seedling w/ nodules Rosidae sensu lato – This large group includes a great amount of variety, including two prominent families of north-temperate wind-pollinated trees. Wind-Pollination Syndrome (syndrome: group of independent traits affected by same selective agent) 1) flowers appear before leaves are out 2) flowers often in catkins “Catkin” – elongate, often dangling inflorescence of unisexual flowers typical of many wind-pollinated trees. Also called ‘ament’ hence the old term ‘Amentiferae’ (latin: ament - bearing) for wind-pollinated plants bearing catkins. 3) Plants often with separate staminate and pistillate flowers (plants monoecious or dioecious) – this permits a greater investment in male function than would be possible in hermaphroditic flowers. 4) large number of flowers (especially males) 5) Big stamens produce lots of pollen 6) Stigmas large and plumose or roughened (papillate) to catch pollen 7) Ratio of pollen to ovules VERY HIGH (up to 6,000 to 1) 8) individual flowers small and inconspicuous - without parts for attraction 9) Flowers without scents or rewards (to attract pollinators) Fagales – clade of wind pollinated trees - OVERHEAD Betulaceae (6 gen/157 spp) Birch family 1) trees or shrubs - mostly north temperate - Alders (Alnus) with N-fixing nodules on roots that house Frankia bacteria 2) Leaves simple, alternate, usually with doubly serrate margins 3) Flowers unisexual; plants monoecious DEMO – lvs of Betula, Corylus - flowers subtended by bracts (1 main bract subtends the inflorescence with typically 2 bracteoles subtending each flower - flowers of both sexes usually in catkins (sometimes males only – e.g., Corylus) - tepals 1-4, sometimes lacking and always very reduced - stamens 1-4 - ovary inferior; carpels 2 fused 4) fruit: nut (animal dispersed), samara (wind dispersed), or achene nut: hard, dry, indehiscent, usually with a single seed --> [Take a moment to catch up on fruit types: follicle, samara, berry, achene] floral formula: male * Te 0 or 4, A 4, G 0 (Te = tepals) female * Te 0 or 4, A 0, G 2 nut, samara, or achene [carpels fused] Page 27 4/13/18 Fagaceae (9 gen/900 spp) Oak family 1) trees or shrubs - mostly northern hemisphere, temperate to subtropical 2) leaves simple, alternate 3) Flowers unisexual; plants monoecious DEMO – Quercus branch w/ catkins - tepals usually 6; always very reduced - male flowers in catkins; 4-40 stamens per flower - female flowers solitary (Quercus), or clustered (2-3) in leaf axils (Castanea, Fagus), or at base of catkin (e.g., Castanea, Notholithocarpus) and surrounded by an involucre of many overlapping bracts; this structure is often described as a “cupule” (as in text) - carpels typically 3 (-6), connate. - ovary inferior - of 3 fused carpels, each with 2 ovules - all but one ovule aborts. 4) Fruit: nut (animal dispersed) Floral formula: male * Te 6, A 4-40, G 0 female * Te 6, A 0, G 3 (-6) nut [carpels fused] Show slides of birches and Oaks and read from Aldo Leopold: ‘Bur Oak’ Page 28 4/13/18 Week 3; Friday Announcements: - First lecture exam next Friday; material through today’s lecture - Review session next Wednesday here at 6:30-7:20. Lecture: Plant Breeding Systems An essay by Joseph Wood Krutch: “The Moth and the Candle” (p.79 essay on yuccas and yucca moths) not enough time to read this in future Plants are incapable of reproductive “behavior” in the sense that animals behave to find and select mates. However, they have evolved a much greater array of reproductive systems than animals due to the fact that - most flowering plants are bisexual - sexual expression can vary over time and space - plants rely on intermediary agents to transfer pollen (containing the sperm) - plants have less rigidly controlled developmental systems and can reproduce vegetatively from many parts Asexual reproduction - reproduction of genetically identical individuals from a single parent plant - no analog in vertebrate animals exists for this, although it is quite common in insects (e.g., aphids), where it still involves the reproductive system (parthenogenesis) Asexual reproduction offers a competitive advantage to individuals particularly well- adapted to the local environment, because all offspring will be genetically identical to their parent. Asexual reproduction can be divided into two basic mechanisms: Cloning or vegetative reproduction- starting new plants from vegetative parts of another plant - rhizomes/stolons – lateral underground/aboveground shoots - tillers - lateral shoots at base of plants that produce adventitious roots - bulblets – little bulbs from the base of big bulbs - bulbils – formed in inflorescence where