2 Gymnosperms seed bearing plants – but “naked seeds” often borne on conesdo not produce flowers - angiospermsGymnosperms-reduced male gametophyte(development of pollen grains)-internal fertilization-reduced female gametophyte(development of ovules)-naked seeds-advanced vascular tissuecomprised of tracheids-woody-perennialAngiosperms-reduced male gametophyte(development of pollen grains)-internal fertilization-reduced female gametophyte(development of ovules & an embryo sac)-seeds – borne in fruits-development of flowers-advanced vascular tissue with tracheids andvessel elements-herbaceous and woody-annuals and perennials
3 Gymnosperms Phylum Ginkgophyta - ginkos only one species left – Ginkgo bilobadeciduous leaves - fanlike formationtolerates air pollution welltrees bear fleshy seeds that smell rancidPhylum Coniferophyta – largest group“cone-bearing”600 species of conifersmany are large treesmost are evergreens – retain their leaves throughout the yearCycas revolutaGinko bilobaWelwitschia mirabilis.Ephedra.
4 Phylum Cycadophyta found in subtropical and tropical regions often confused with young palmsstout trunk with compound leavesmost are less than 2m tallMacrozamia = 18m tall9 to 10 genera – ~300 species total~25% are considered endangeredtake a very long time to growstout, cylindrical trunk that does not branchleaves are pinnate (“feathers” on a bird) are grow directly from the trunkcentral leaf stalk with parallel “ribs” emerging from the sidesleaves grow from the top of the crown downPhylum CycadophytaSago palmCycas revoluta
5 Phylum Cycadophyta require very specific pollinators – usually beetles produce seed and pollen cones on separate plants = dioeiciouspollen cones are spirally arranged microsporophylls that bear clusters of microsporangiapollen cone can be very largeseed cones are variable in morphologyvariety in number and shapesrequire very specific pollinators – usually beetlesseeds contain neurotoxins and should not be eatenPhylum CycadophytaCycas revoluta pollen coneseed cone openedCycas circinnalis seed coneCycas circinnalis pollen cone
6 Phylum Gnetophyta 3 genera of gymnosperms: 1. Gnetum - are mostly vines or shrubs with very broad leaves30 speciesnative to southeast Asia, tropical Africa and the Amazon basinseeds are eaten2. Ephedra – shrubs and bushes40 speciesinhabit desert regions in northern Mexico and southwestern USreduced scale-like leavesused in the production of ephedrine3. Welwitschia – only one speciesWelwitschia mirabilisdeserts of South Africaleaves grow perennially – becoming increasingly longerlargest leaves in the plant kingdomEphedra sinicaWelwitschia mirabilis
7 Phylum Gingkophyta contains a single living species – Gingko biloba “living fossil”also known as the “maidenhair tree”woody treebroad leaves – very distinct shapetrees are dioeciousmicrosporangiate treesmegasporangiate treesno ovulate cones- ovules occur in pairs at the ends of a short stalked megasporophyll – unprotected at maturitywhen the female tree produces its seeds – contain butyric acid which has a putrid odorPhylum GingkophytaGingko biloba
8 Phylum Coniferophyta 575 species pine trees, firs, spruces, hemlocks, redwoods, cedars290 million years oldlargest genus – Pinusover 100 living speciespredominant in the northern hemispherealso planted in the southern hemisphere – only the Merkus pine occurs there naturallyworld’s oldest known living organism – bristle cone pine (4,600 years old)
9 Phylum Coniferophyta: the Conifers Douglas fir. “Doug fir” (Pseudotsuga menziesii) provides more timber than any other North American tree species. Some uses include house framing, plywood, pulpwood for paper, railroad ties, and boxes and crates.
10 Pacific yew. Thebark of Pacific yew(Taxa brevifolia) is asource of taxol, acompound used totreat women withovarian cancer.Theleaves of aEuropean yewspecies produce asimilar compound,which can beharvested withoutdestroying the plants. Pharmaceutical companies are now refining techniques for synthesizing drugs with taxol-like properties.
11 Bristlecone pine. This species (Pinus longaeva), which is found in the White Mountains of California, includes some of the oldest living organisms, reaching ages of more than 4,600 years. One tree (not shown here) is called Methuselah because it may be the world’s oldest living tree. In order to protect the tree, scientists keep its location a secret.
12 Sequoia. This giant sequoia (Sequoiadendron giganteum), in California’s Sequoia National Park weighs about 2,500 metric tons, equivalent to about 40,000 people.Giant sequoias are the largest living organisms and also some of the most ancient, with some estimated to be between 1,800 and 2,700 years old. Their cousins, the coast redwoods (Sequoia sempervirens), grow to heights of more than 110 meters (taller than the Statue of Liberty) and are found only in a narrow coastal strip of northern California.
16 Pollen Cones Male Pine Cone considered to be simple cones microspores(pollen)microsporangiummicrosporophyllconsidered to be simple conesone single cone axis bearing modified leaves known as microsporophyllscones typically occur in clusters near the ends of branchespollen is liberated to the wind and blown awaypollen has one cell and two large air bladders that increase its buoyancy in airwind dispersal is inefficient – so few pollen grains actually land on the ovulate conebut conifer forests are very dense
17 Microsporangium containing microspores (pollen) Pine pollen cone - microsporophyll & a microsporangium (containing microsporocytes).Microsporangium containing microspores(pollen)MicrosporangiumWith pollen grainsmicrosporophyllPine pollen with male gametophyteGerminating pine pollenair bladdergenerative cell(becomes 2 sperm)tubecell
19 Seed cones more complex than pollen cones compound cone each consists of a cone axis with scalesthe scales bear leaves that are called sterile bracts in addition to sporophyllsscale is a fused megasporophyll with two ovulesmegasporophyll also called an ovulate scalesterilebractmegasporophyll
20 Seed cones megasporophyll ovules integument bract Pine seed cone with ovulate scale (megasporophyll) and ovuleovulesmegasporophyllbractmega-sporeintegument
21 Developing ovulate scale (megasporophyll) in a young pine seed cone bractFuture ovule2 Archegonia (developed from the megaspore) within the ovulefemale gametophyteegg nucleiArchegonia in pine ovule with egg nucleus
22 Female Pine Cone Male Pine Cone microsporophyll microsporan- gium microspore(pollen)microsporan-giummicrosporophyllFemale Pine Cone
23 The Pinus genus is divided into two subgenera that are separated by the presence of either one vascular bundle in the leaf (subgenus Strobus) or two (subgenus Pinus).Subgenus Pinus with two vascular bundlesVascular bundlesVascular bundleSubgenus Strobus with one vascular bundle