Biology 200B 1st Edition Lecture 27Chapter 37 Plant Form and Function I. Surface area: volumeII. Plant StructureIII. Organsa. Rootsb. Shootsc. Stem and leaves Chapter 37 continued Modified stems- Potatoes are stem tubers- Stems modified for starch storage - “Eyes” are dormant axillary buds - Sweet potatoes are root tubers - Also modified for starch storage - No nodes, buds only at one end Modified leaves - Onion leaves store food - Tendrils of climbing legumes - Succulent leaves modified for water storage - Bracts – colorful modified leaves surrounding flower Tissue systems - Dermal – thin (1-2 cells); covering in waxy cuticle; may include hair, trichomeso Protection against water loss, pathogens, herbivoreso Stomata for gas exchange - Vascular – xylem (water/minerals from soil); phloem (water/sugars)o Xylem: 2 kinds of conducting cells1. Tracheids – narrow, overlapping, pits2. Vessel elements – wide, end-to-end, perforationso Both are dead at functional maturity o Phloem: Sieve-tube members are conducting cells; alive at functional maturity, but “stripped down”; missing some organelles (nucleus, vacuole, etc)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Ground – storage, support, photosynthesis Plant cell types - 3 major types: Parenchyma, collenchyma, sclerenchyma Parenchyma:- Least specialized – a typical plant cells - Thin primary cell walls and no secondary cell walls- Responsible for many metabolic functions: photosynthesis, storage of sugar/ starch - Found in – ground tissue; sieve tube members and companion cells of phloem; ground tissue (mesophyll) of leavesCollenchyma:- Have thickened primary cell walls - Found in ground tissue of stems, roots and also leaf petioles- Function in support, but still flexible enough to elongate and allow growth Sclerenchyma:- Specialized for support – very strong and rigid- Secondary cell wall thickened with lignin - May be dead at functional maturity- Found in ground tissue and vascular tissue Plant growth is indeterminate because of meristems – regions of embryonic tissues- Meristems divide to form new cells that can become specialized for different purposes - Primary growth – apical meristems - Secondary growth – lateral meristems Primary growth - Growth from apical meristems- Occurs in all vascular plantsSecondary growth - Occurs in stems and roots of some vascular plants - Produces increase in girth - Produces “wood” and “bark”- Involves lateral meristems- Stems and roots of: some angiosperms; some gymnosperms; increases girth of stem androots- Arises from special meristems called cambiums o Cork cambium (periderm; part of bark)o Vascular cambium (secondary xylem mostly;
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