The shoot system of plants: the leafleaf lateral outgrowth of the stem distinctive characteristics: green contains chlorophyll for photosynthesis flat ideal for intercepting light wide for wide distribution of stomates origin: leaf primordia with actively dividing cells that will develop into a new leaf marginal meristem- gives rise to the leaf blade and petiole main functions: for photosynthesis (food manufacturing) for transpiration (loss of excess water) for gas exchange (entry of CO2, and release of O2 ) morphology: parts: most dicots have petioles PETIOLATE most monocots DONT have petioles SESSILE

leaf venation pattern formed by the leaf veins netted/ reticulate 1 or more prominent veins from which smaller veins (veinlets) branch off; exhibited by DICOTS parallel/ striate 1 or few longer veins that are parallel to each other; exhibited by MONOCOTS

leaf symmetry aDaxial side dorsal (upper surface) aBaxial side ventral (babang surface) dorsiventral distinct adaxial and abaxial sides (DICOTS) isolateral the adaxial and abaxial sides look the same (MONOCOTS)

leaf type leaf blade configuration simple blade is all in one unit compound blade is composed of a number of leaf-like parts - trifoliate (Vigna radiata) - pinnate (Gliricidia sepium) - polypinnate (Moringa oleifera) - palmate (Brassaia actinophylla)

* techniques to easily identify the leaf type: -first look for the stem kasi anything that will arise from the stem would be a leaf.. except for flowers, stem tendrils and fruits, ha? oki?! -next, look carefully at the blade/ lamina of the leaf titigan at sundan ang blade kung konektado yung blade, kahit mejo mukhang hiwahiwalay, basta as long as may connection, it is considered as a simple leaf kung hiwahiwalay naman ung blade at may series ng leaf-like structures, e di compound nay un okey?! good!! * examples:

leaf stem Simple leaf

Coffea sp.

Simple leaf(arrow connection of the blade)

Carica papaya

Compound leaf

Brassaia actinophylla Phyllotaxy leaf arrangement alternate 1 leaf : 1 node (Carica papaya) opposite 2 leaves : 1 node (Coffea sp.) whorled 3 or more leaves : 1 node (Allamanda cathartica)

petiole

Alternate

node Carica papaya

1node Opposite

2Coffea sp.

node1 2 4 3

Whorled

Allamanda cathartica anatomy: 3 main tissue systems: dermal tissues epidermis ground tissues mesophyll vascular tissues xylem and phloem (veins)

epidermis may be: simple single layered multiple multiple layered - non-chlorophyll containing cells - covered with CUTICLE to minimize water loss stoma/ta 2 guard cells + pore types of stomatal distribution: epistomatic stomatal concentration on the adaxial side hypostomatic stomatal concentration on abaxial side amphistomatic stomatal concentration on both sides mesophyll to facilitate rapid gas exchange esp. for photosynthesis palisade mesophyll next to the epidermis (adaxial); columnar/ rectangular parenchyma cells with numerous chloroplasts (CHLORENCHYMA) *not present/not distinctly seen in MONOCOTS* spongy mesophyll next to the palisade layer (abaxial); irregularly shaped parenchyma cells with lots of intercellular spaces (AERENCHYMA)

vascular bundle location of xylem and phloem: xylem up phloem down

xeromorphic adaptations: to be able to survive dry conditions Nerium oleander - multiple epidermis with thick waxy cuticle - stomatal crypts with TRICHOMES (hairy out growths) which help in reducing water loss - bilayer palisade mesophyll

guard cell

trichomes Stomatal crypt

Oryza sativa -bulliform cells/ motor cells inflated cells (high water concentration= fully expanded leaf: low water concentration= leaf margins roll)

bulliform cells

metamorphosed leaves with specialized functions spine for protection (Livistona rotundifolia anahaw) insect trapper for additional nutrients (Nepenthes elata pitcher plant) enlarged/ inflated petiole- for floating/ buoyancy (Eichhornia crassipes water hyacinth) leaf tendril for additional support (Flagellaria indica balingwai) bulb composed of overlapping leaf sheaths food storage (Allium cepa onion) colored bract/ semaphyll for attracting pollinators (Bougainvillea spectabilis, Mussaenda sp.) pseudostem enlarged base of petiole for additional support (Musa sapientum banana) vegetative leaves for asexual reproduction (Kalanchoe pinnata kataka-taka) bud scale- for protection of developing bud (Ficus elastica)