Plant Organization

Marjay L. MaganaIII-1 Aluminium

Sir Sherwin Maningas

•multicellular, primarily terrestial eukaryotes with well develop tissues.

•autotrophic by photosynthesis, contain chlorophylls a and b , carotenoids, and other pigments

•store starch in chloroplast, cell wall contains cellulose

•protect the developing embryo from drying out by providing it with water and nutrients within the female reproductive structure.

•alternation of generation's life cycle (2-generation life cycle : sporophyte and gametophyte phases)

•consist of three groups: liverworts (Hepatophyta), hornworts (Anthocerotophyta), and mosses (Bryophyta)•lack vascular tissue•no true roots, stems, and leaves; anly root-like, stem-like, and leaf-like structures

•usually small, the largest is no more than 20 cm tall•found in moist habitats•dominant independent, photosynthetic gametophyte•dependent sporophyte, attached to and derives its nourishment from the gametophyte )

Seedless Vascular Plants-include the ferns (Pteridophyta) and its allies-whisk ferns (Psilotophyta), quillworts, club and spike mosses (Lycopodophyta), and horsetail (Equisetophyta)-with vascular tissues-xylem and phloem-with true roots, stems, and leaves-dominant pothosynthetic sporophyte-independent gametophyte

Seed Vascular Plants-include the gymnosperms (naked seed) and angiosperms (enclosed seed)-with vascular tissues-xylem and phloem-with true roots, stems and leaves-dominant photosynthetic sporophyte-dependent gametophyte (seed vascular)

1.Gymnosperms -cone-bearing plants-include conifers or pine (Pinophyta), cycads (Cycadophyta), ginkgo(Ginkgophyta), and gnetophytes (Gnetophyta)

2.Angiosperms -fruit-bearing or flowering plants (Magnoliophyta)-divided into dicot ( class Magnoliopsida ) and monocot (class Liliopsida)

a. Dicot -more primitive than the monocots-embryo has two cotyledon-floral parts in 4's or 5's or multiples of 4's or 5's-mostly woody, some herbaceous stems-oval or palmate leaves with net-like venation-taproot stem

b. Monocot -more advance by the dicots-embryo has one cotyledon-floral parts in 3's or multiples of 3's-usually herbaceous, soft and green stems-narrow shaped leaves with parallel venation-fibrous root system

•classified into primary and secondary tissues responsible for primary and secondary growth respectively-primary growth refers to increase in height and secondary growth refers to increase in diameter and formation of woody structure•divided into four types: meristems, dermal, ground fundamental, and vascular

•also called embryonic or growth tissue•composed of unique, differentiated small actively dividing cells•have thin walls and large nuclei•lack conspicuous vacuoles and intercellular spaces

1.Terminal or apical meristems-located at the tips of roots and meristems-responsible for stablishing patterns and producing new, genetically health cells

2.Intercalary meristems-portions of apical meristems separated from the apex during development-lie below the node and at the base of stem of grasses-disappear when transformed into permanent tissue

3.Lateral meristems-composed of initial cells that divided chiefly in one plane-increase the diameter of the organ

Derivatives of Meristems1. Protoderm -forms the dermal tissues; irreplaceable2.Procambium-forms the vascular tissues3.Ground meristems -forms the ground tissues

Dermal Tissues

•cover of body plant•responsible for absorption of water and minerals, secretion of cuticle, protection against herbivores, control gas exchangehave few intercellular space

1.Cuticle-composed of fatty material, water-proof cutin-covered by epiticular wax-outer covering of leaves, particularly the upper surface-protects the plant for dessication and microbes2.Epidermal Cells-in leaves and young green stems, the only intercellular spaces are the stomata surrounded by guard cells-responsible for gas exchange and cellular recognition

3.Trichomes-unicellular or multicellular outgrowths from the epidermal cells, eg. cotton fibers, menthol of peppermint, and root hairs-responsible for nutrition and absorption and protection from herbivores and humans

Fate of Epidermis-short-leave in many plants-repalce by a secondary dermal tissue- the periderm

Fundamental Ground Tissues

form the bulk of the of the softer parts of plantsinclude the pith and cortex of stem, leaf tissues except for epidermis and veins, and major portion of fruitsresponsible for storsge, basic metabolism and support

Parenchyma( Greek, para , beside; en+chein,to pour in)-most common and most abundant plant tissue-occur in all organisms of higher plants-have long-lived protoplast, large vacuoles ,and thin walls

1.Chlorenchyma Cells-contains chloroplast for photosynthesis

2.Aerenchyma Cells-parenchyma with prominent intercellular spaces to improve gas exchange and provide maximum support

3.Transfer Cells-parenchyma specialized for short-distance transport of solutes-occur in areas of high solute transport along the conducting cells of xylem and phloem

Collenchyma (Greek , kolla,glue) -composed of elongated cells with unevenly thickened stretchable cell walls, cells are often in standards or as a cylinders beneath the epidermis-support the growing regions of the shoot-expanding leaves, petiole,and elongating stems