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Flowers & Plant Hormones SEPALS cover and protect the flower parts when the flower is a bud PETALS play an important role in attracting animal pollinators FILAMENT CALYX (group) COROLLA ( group) thin stalk attached to anther saclike structure ANTHER STAMENS Pollen grains form within pollen sacs in the anther male floral parts Parts CARPEL female reproductive unit consist of a single carpel or a group of fused carpels STIGMA STYLE pollen grains land pollen tube grows contains one or more OVULES PISTIL EGG and 2 POLAR NUCLEI, along with several other nuclei, are formed in the ovule OVARY Both egg and polar nuclei participate directly in fertilization. develop into seeds female floral parts has 4 kinds of floral organs; SEPALS, PETALS, STAMENS, PISTIL COMPLETE FLOWER could also be a perfect flower Types INCOMPLETE FLOWER lacks one or more of parts could not be a complete flower PERFECT FLOWER only reproductive parts are present Insect-pollinated Pollination (by flyers) often yellow or blue and have a scent often yellow, orange, or red and DO NOT have a strong scent Bird-pollinated Bat-pollinated embryonic shoot; and one or two seed leaves, or cotyledons Cotyledon mature embryo within the seed consists of a short embryonic root, or radicle Radicle Seed Parts Foliage leaf Plumule shoot apex, or terminal bud, located above the point of attachment of the cotyledon(s) Hypocotyl Seeds often have white petals and are scented short portion of the embryonic shoot connecting the radicle to one or two cotyledons peanuts, coconuts, brazil nuts are not nuts but seeds Fleshy berries, grapes, tomatoes, banana SIMPLE FRUITS Dry coconut, wheat, beans, peanuts, acorn develop from a single flower with many separate ovaries AGGREGATE FRUITS strawberries, watermelons, atis fruits (sugar apples/Anona) Fruits develop from the ovaries of many flowers growing in close proximity on a common axis MULTIPLE FRUITS pineapple, jackfruit major part of the fruit consists of tissue other than ovary tissue ACCESSORY FRUITS apple process of seed sprouting maturity of embryo Germination INTERNAL FACTORS chemical inhibitors (presence/absence) hard, thick seed coats (presence/absence) EXTERNAL FACTORS oxygen, water, temperature, and light RHIZOME horizontal underground stem TUBER fleshy underground stem enlarged for food storage BULB modified underground bud with fleshy storage leaves attached to a short stem short, erect underground stem covered by papery scales CORM horizontal aboveground stem with long internodes STOLON Asexual Reproduction Structures DETACHABLE PLANTLETS leaves have meristematic tissue along their margins and give rise to detachable plantlets roots develop adventitious buds that develop into suckers.they produce additional roots and may give rise to new plants. SUCKERS APOMIXIS production of seeds and fruits without sexual reproduction sexual - union of gametes, asexual - identical, etc. Difference between asexual and sexual directional growth response TROPISMS Phototropism to the direction of light Gravitropism to influence of gravity Thigmotropism to contact with a solid object Shoot apical meristem, young leaves, seeds AUXINS Stem elongation, apical dominance, root initiation, fruit development (e.g., IAA) Young leaves and shoot apical meristems, embryo in seed GIBBERELLINS Seed germination, stem elongation, flowering, fruit development Various sites in plants Cell division, delay of leaf senescence, inhibition of apical dominance, flower development, embryo development, seed germination CYTOKININS (e.g., zeatin) Plant Hormones Stem nodes, ripening fruit, damaged or senescing tissue ETHYLENE Fruit ripening, responses to environmental stressors, seed germination, maintenance of apical hook on seedlings, root initiation, senescence and abscission in leaves and flowers ABSCISIC ACID all cells that contain plastids (leaves, stems, roots) Seed dormancy, responses to water stress Shoots (leaves and flower buds), seeds, fruits Light-mediated gene expression, cell division, cell elongation, seed germination, vascular development BRASSINOSTEROIDS (e.g., brassinolide) any response of plants to the duration and timing of light and dark Flowering is a photoperiodic response in many plants Photoperiodism Short-day plants detect the lengthening nights of late summer or fall and flower at that time Long-day plants detect the shortening nights of spring and early summer and flower at that time Intermediate-day plants circadian rhythm flower when exposed to days and nights of intermediate length regular period in an organism’s growth or activities that approximates the 24-hour day and is reset by the rising and setting of the sun. 2 of circadian rhythms are the opening and closing of stomata and sleep movements genetic diversity sexual, costly for survival in changing environ genetic similarity asexual, advantageous if stable environ
