Announcements. Lab Quiz #1 on Monday: (30pts) conifers + cones, vegetative morphology. Study: Display case outside HCK 132 with labeled conifers

Transcription

1 Announcements Lab Quiz #1 on Monday: (30pts) conifers + cones, vegetative morphology Study: Display case outside HCK 132 with labeled conifers Movie: Sexual Encounters of the Floral Kind Intro to Keying/Greenhouse tours: dichotomous keys - progressive series of paired, alternative statements that lead to the identification of an organism

2 Review of the previous lecture Gr. Morph = form (structure, size, shape) + logy = study of Vegetative morphology: any part of the plant involved in growth, development, photosynthesis, support, etc., but NOT involved in sexual reproduction Reproductive morphology: any portion of the plant involved in or a direct product of sexual reproduction

3 Correction: perigynous Ovary position

4 Mosses Lycophytes Green plants (Kindgom Plantae) Green plants Embryophytes (land plants) Bryophytes Tracheophytes (vascular plants) Liverworts Hornworts Seed plants Green algae Ferns Gymnosperms Angiosperms

5 Phylogeny of Green Plants Green algae Green plants Embryophytes (land plants) Embryo Cuticle Sporopollenin

6 Phylogeny of Green Plants Green algae Green plants Embryophytes (land plants) Embryo Cuticle Sporopollenin

7 Pop Quiz According to the phylogenetic tree shown in the previous slide, the group green algae is: A. Monophyletic B. Paraphyletic C. Polyphyletic D. I have no idea

8 Phylogeny of Land Plants Embryophytes (land plants) Bryophytes Tracheophytes (vascular plants) tracheids stomata

9 Phylogeny of Tracheophytes Tracheophytes (vascular plants) Seed plants (Gymnosperms +Angiosperms) Textbook DVD WSJ seeds Textbook DVD WSJ pollen true leaves

10 Phylogeny of Seed Plants Seed plants Gymnosperms Angiosperms Textbook DVD WSJ flowers endosperm reduced female gametophyte carpel bitegmic ovules

11 Generalized Life Cycle in Plants vs. Animals What s the difference between plants and animals?

12 Generalized Life Cycle in Plants Alternation of generations = cycle between haploid (1n) and diploid (2n) phase.

13 Life Cycle: angiosperms (flowering plants)

14 Life Cycle: ferns and fern allies

15 Life cycle: bryophytes The sporophyte generation is dependent on the photosynthetic gametophyte for nutrition Ref.3

16 Variation of life cycle in plants Bryophytes (mosses, liverworts, hornworts) - Most of life is in 1n phase, therefore, a gametophyte (green leafy base) dominant life cycle; sporophyte (brown stalked capsule/sporangium) dependent on gametophyte (grows out of gametophyte and gets all nutrition from gametophyte) Sporophyte produces spores that germinate into gametophytes Ferns and fern allies - sporophyte dominant; gametophyte free-living, but small and short-lived. Leaves = sporophyte, free-living. Spores germinate from sporangia on underside of leaves (sori) and produce small, green, free-living heart-shaped gametophytes Gametophyte with separate structures that produce egg & sperm; lives ~1 year, reproduces, then dies Sporophyte dominant life cycle: lives longer and larger and reproduces many years Seed plants (Angiosperms and Gymnosperms) - sporophyte dominant; gametophyte dependent on sporophyte and very reduced and short-lived. Microsporangia in pollen-bearing structures (pollen cones or anthers) that produce male gametophyte, short-lived and inside the pollen grain, which consists of 2-3 cells, one cell becomes sperm. Megasporangia in ovules that produce female gametophyte in cone ( gymnosperms ) or ovary (angiosperms) and produces the egg. Spores grow into pretty small gametophytes which are contained within the parent plant (inside cones or flower).

17 Some key terms in the angiosperm life cycle embryo vs. embryo sac Embryo (2n): young sporophyte, from the first cell after fertilization until germination of the seed (in seed plants) or emergence from protective gametophytic tissues (other land plants); zygote. Embryo sac (1n): female gametophyte of the angiosperms (flowering plants).

18 Some key terms in the plant life cycle Meiosis = reductive nuclear division process that reduces the chromosome number of a cell by half (from a diploid cell to 4 haploid daughter cells). Mitosis = nuclear division that maintains the parental chromosome number for daughter cells; the basis for growth in size and asexual reproduction in plants. Fertilization = fusion of the sperm nucleus and the egg nucleus to form a zygote. Zygote (2n) = the cell formed by fusion of the gametes (sperm [1n] and egg [1n]) at fertilization; embryo. Spore (1n) = the first cell of the gametophyte generation; product of meiosis. Sporophyte (2n) = diploid, spore-producing generation of the plant life cycle, that produces structures called sporangia (singular, sporangium). Gametophyte (1n) = haploid, gamete-producing generation of the plant life cycle, that produces structures/sex organs gametangia (male: antheridium, produce sperm; female: archegonium, produce eggs).

19 Some key terms in the seed plant life cycle Seed plants (angiosperms and gymnosperms) Sporophyte independent and dominant. Gametophyte dependent on sporophyte and very reduced and short-lived. Microsporangia in pollen-bearing structures that produce male gametophytes; in pollen cones (gymnosperms) or anthers (angiosperms). Male gametophytes = short-lived and inside the pollen grain; 2-3-celled, 1 cell becomes 2 sperm. Megasporangia in ovules that produce female gametophytes, which produce eggs; in cones (gymnosperms) or ovaries (angiosperms). Spores grow into small gametophytes which are contained within the parent plant (inside cones or flower).

20 Which comes first: pollination or fertilization? Pollination = transfer of pollen from anther to stigma. Fertilization = fusion of sperm nucleus and egg nucleus. Pollination occurs only in seed plants! Fertilization occurs in all sexually reproducing organisms. In seed plants, pollination must occur before fertilization!

21 Mosses Lycophytes Summarize the synapomorphies for major groups of land plants Green plants Embryophytes (land plants) Bryophytes Tracheophytes (vascular plants) Liverworts Hornworts Seed plants Green algae Ferns Gymnosperms Angiosperms

22 Pollination Syndromes Pollination syndromes Sexual Encounters of the Floral Kind Handout to accompany film Biology 117/317 Wind Pollination: 1) flowers appear before leaves are out 2) large number of flowers (especially males), often in catkins 3) individual flowers small and inconspicuous - without parts for attraction 4) Big stamens produce lots of pollen 5) Stigmas large and plumose or roughened (papillate) to catch pollen 6) Ratio of pollen to ovules VERY HIGH (up to 6,000 to 1) Many different kinds of insects function as pollinators; often these involve very different floral characteristics: Bees, butterflies, etc.: 1) flowers showy, with brightly colored petals 2) flowers usually with some food reward, two common ones are: pollen - protein rich reward nectar - rich in nutrients (e.g., amino acids and sugars) 3) flowers often with strong favorable scent during the day 4) flowers often with ultraviolet markings visible only to the insects (not to humans)

23 Pollination Syndromes Moths: 1) flowers often white 2) flowers open and scent released in the evening or at night 3) nectar reward 4) flowers often long and tubular to limit access only to long tongued moths Carrion flies (Blowflies): 1) flowers purple or brown or greenish-brown 2) flowers often close to the ground 3) scent strong and foul (like dead animal) Buzz pollination by bees: 1) no nectar reward (pollen sole reward) 2) connivent anthers (anthers held together) at center of flower 3) anthers opening by terminal pores; pollen shakes out when the bee buzzes the flower Birds often pollinate flowers, too: Hummingbirds (found in North and South America only): 1) flowers with long tubular corollas 2) flowers usually red 3) nectar reward in large quantity, rich in sugars (few other nutrients) 4) flowers often dangle away from plant so that bird can reach it while hovering In other parts of the world different birds, including Honeycreepers (Hawaii), Honeyeaters (Australia) and Sunbirds (S. Africa) act as pollinators. Flowers adapted to these birds differ from those adapted for hummingbirds by having a landing platform for the birds to perch on, because they cannot hover. The flowers still have long tubular corollas and lots of sugar-rich nectar.