14 Horsetails Few Species alive now Needle Like Branches Small leaves grow in circle around jointsSmall leavesgrow flat against stemStem contains Silica
15 Club Mosses Only a few hundred species Resembles branch of a pine tree Ground pineGrows in spiral around stem
16 Seed Plants Have Vascular Tissue Use Pollen and Seeds to reproduce Xylem – carries water and mineralsPhloem – carries food (sugars)Use Pollen and Seeds to reproducePollen – male reproductive cellSeeds – embryo, food supply, seed coatGymnospermsSeeds not protected by fruitAngiospermsProduce FlowersSeeds protected by fruit
18 Seed Dispersal Seeds must be dispersed to prevent competition WaterSunlightMineralsDispersed byWindAnimals
19 GerminationNeeds- correct moisture, correct temperature, correct time – some seeds are dormant first
20 Roots Tip Covered by a root cap Protects root during growth New cells develop behind root capRoot hairsTinyAbsorb water, mineralsAnchor plant in soilXylemPhloemFibrous Roots - spreadingTaproot - deep
22 LeavesConduct Photosynthesis Lose water from stomates during transpiration Guard cells control amount of water lost
23 GymnospermsGinkgoSeed Not Protected by a fruit Needle like or scale like leaves Deep roots systemCycadtropicalConiferLargest groupCone bearingGnetophyteDeserts, tropical rain forestsCan live 1,000 yrs.
29 TropismsA plant grows toward a stimulus – positive A plant grows away from a stimulus – negative Touch – Thigmotropism Light – Phototropism Gravity – Gravitropism or Geotropism Hormones – Auxin – causes cells to lengthen on side away from light. Plant bends toward light.
30 Seasonal Changes Photoperiodism – response to length of day vs. night. Critical Night LengthShort Day Plants – Bloom when daylight is shorter autumnLong Day plants – Bloom when daylight is longer – spring and summerDay Neutral – No effect
31 Life Spans of Angiosperms AnnualsComplete cycle in one growing seasonherbaceous stemsBiennialsYear one –stems, leavesYear Two –flowers, fruits, seedsPerennialsFlower every yearMost have woody steamsome have herbaceous stemsleaves and stems die each winter, but new are produced in spring.