The Plant Body Monocots vs Dicots Leaf Traces
The Plant Body
Monocots vs Dicots
Leaf Traces • At each node, one or more vascular bundles diverge from the cylinder of strands in the stem, cross the cortex and enter the leaf or leaves attached at that node • The extensions from the vascular system in the stem toward the leaves are called the leaf traces • The wide gaps or regions of ground tissue above the level where leaf traces diverge toward the leaves are called leaf gaps
Sympodia – a leaf trace and the vascular bundle it is connected to
Plant habitat and leaf structure • mesophytes - plants that require abundant soil moisture and a fairly humid environment - the most common plants - typically have fairly well developed epidermis, especially on upper surface of leaf, stomata on both sides of leaf • hydrophyte - plants that depend on a very abundant supply of water or which grow wholly or partially submerged in water - have thin epidermis, stomata only on upper surface • xerophyte - plants adapted to arid habitats - very thick epidermis, stomata open to stomatal crypts with protective hairs
Mesophytes
Mesophyte Leaf
Hydrophytes
Hydrophyte Leaf
Xerophytes
Xerophyte Leaf
Monocot vs. Dicot Leaves
Dicot stomata
Red Oak Leaves Shade Leaves Sun Leaves
Flowers and Fruit
Flower Structure • Generalized flowers - 2 outer sets of sterile parts, 2 inner sets of fertile parts • Outer sterile part - sepals, collectively the calyx - may do photosynthesis, protect flower, usually like leaves in texture, protect bud - form outer covering of bud • Next sterile part - petals - not like leaves in texture, usually not green, collectively called corolla - petalloid - petal like in appearance • Both sepals and petals can be fused - so sepals joined together, petals joined together • Perianth - calyx and corolla together - used when the two cannot be distinguished - sometimes sepals and petals are called tepals for perianth if very similar in appearance – like in Tulips • If only one set of sterile parts, they are always called sepals; sometimes whole perianth is missing • First fertile parts - stamens - male – androecium - Can be sterile and modified to look like petals • Innermost fertile parts - pistils, female - gynoecium
Wild Rose
Yellow rose – many “petals” are actually modified sterile “petalloid” stamens
Carpels and Ovaries • Flowering plants always have enclosed ovary wrapped in a carpel - nonflowering plants don't • Carpel is highly modified leaf - a simple carpel has one ovary • Pistil may be made up of one carpel or several fused carpels • The bottom part is called the ovary, with stigma at top to receive pollen, style connects them fused carpels may have separate style and stigma or they may all be fused
Helleborus – five separate carpels
Malus – crab apple – typical flower structure
Plant Sexuality • Monoecious - separate flowers for male and female both on one plant - corn • Dioecious - male and female plants are separate - separate sexes – gingko, holly • Perfect flower - flower has stamens and carpels – bisexual flowers • Imperfect flower - lacks either stamens or carpels - will be staminate or carpellate (pistillate) • Complete - has sepals, petals, stamens and carpels • Incomplete - lacking one of the 4 main flower parts
Complete and Incomplete Flowers
Jatropha – monoecious but insect pollinated Female left, male right
Dioecious - Holly Female flower Male flower Berries on female
Inflorescence terms • Often flowers, especially small flowers, are gathered into a structure known as an inflorescence – an aggregation of flowers on a single flowering branch • bract - more or less modified leaf that subtends flower or flower groups - bract can look like normal leaf • bract can also look like petal - petalous - dogwoods have big white "petals" that are really petaloid bracts • peduncle - stalk of cluster of flowers • pedicel - stalk of individual flower • petiole - leaf stalk
Dogwood with petalloid leafy bracts
Types of Inflorescence 1. indeterminant - youngest flower at apex in theory could produce flowers forever some may by fruiting while apex still flowering - include - racemes, panicle, spike, corymb, head, umbel, catkin 2. determinant - oldest flowers at apex moving down younger flowers - cyme, scorpiod cyme
Raceme Larkspur
Panicle Panicum - switchgrass
Spike – prairie blazing star
Corymb Yarrow
Umbel Wild parsnip Queen Anne’s Lace
Sunflower – Composite head inflorescence
Catkin Alder catkin
Scorpoid Cyme Onosmodium
Skunk cabbage inflorescence – a spathe and spadix
Pollination syndromes among the phloxes
Magnolia – beetle pollinated
Honeybee covered with pollen
Scotch broom – bee pollinated
Honeybee pollinating beebalm – Monarda sp.
With visible light with UV light Nectar guides for honeybees
Cyrtid fly pollinating a composite
Stapelia gigantea – carrion fly pollinated
Monarch butterfly pollinating milkweed
Brugmansia – moth pollinated
Hummingbird pollination
Ipomopsis aggregata – hummingbird pollinated
Greater double-collared sunbird
Proteus – pollinated by perching birds
Bat Pollination
Box elder – wind pollinated – female left, male right
Wild oats – Whole plant
Wild oat flower – close up
Fruit Types • A fruit may be defined as a matured ovary • There are two basic fruit types – dry or fleshy. These types arise from the development of the pericarp – outer cover of ovary • The pericarp may become dry and these form dry fruits • The pericarp may also become soft, thick and fleshy – and these form fleshy fruits
Pome - Apples and Pears
Violet flower types
- Slides: 70