Flowering plants (Magnoliophyta) {flowering plant} {angiosperm}| have xylem, flowers with pistils, and fruits with enclosed seeds. Flowering plants are the highest pteropsida.
Angiosperms can lose leaves each fall {deciduous}|.
Day length {photoperiodism} affects flowering. Flowers can appear in winter, in summer, or all year. Photoperiodism can affect tubers and other plant characteristics.
If VRN1 gene is present, 40-degree temperatures for several weeks trigger flowering {vernalization}.
Flowers {flower}| are modified stems. Flowers have receptacle, calyx, sepals, petals, stamen, and pistil.
flower types
Flowers can have stamen, pistils, petals, and sepals {complete flower} or lack something {incomplete flower}.
stamen and pistil types
Flowers can have functional stamen and pistil {perfect flower}, functioning pistil only {pistillate flower}, or functional stamen only {stamenate flower}.
imperfect flowers
Date palm, willow, and poplar have imperfect flowers. Plants can have separate staminate and pistillate plants {dioecious plant}, as in holly trees and pistachio trees. Plants {monoecious plant} can have separate male and female flowers on same plant, as in corn and pecan trees. Plants can have only male flowers at growing-season beginning but later have male and female flowers, as in cucumbers and squash.
temperature
Some flowers have cone-shaped top-surface cells that focus sunlight onto lower-cell petal pigments, making flowers warmer.
Plants can have one flower {solitary flower} per stem.
floret
Plants can have flower clusters {floret} on stems in racemose or cyme form {inflorescence}.
racemose
Florets can start from bottom and go up in spikes, racemes, corymbs, umbels, or heads {racemose inflorescence}. Many stemless florets can attach to long flower stems or peduncles {spike inflorescence}, as in gladiolus. Florets can be on small stems attached to peduncles {raceme inflorescence}, as in snapdragon. Florets can have random stalks and pedicels along peduncles {corymb inflorescence}, so florets make flat round tops, as in yarrow. Corymbs can have pedicels that all arise from one peduncle point {umbel inflorescence}, as in dill. Many stemless florets can arrange as in daisies {head inflorescence} {composite inflorescence}.
cyme
Top florets can open first and bloom downward along peduncles {cyme inflorescence}. Florets can be opposite along peduncles {dischasium cyme inflorescence}, as in baby's breath. Lower florets can be on the same peduncle side {helicoid cyme inflorescence}, as in freesia and statice. Florets can alternate along peduncles {scorpioid cyme inflorescence}, as in tomato and potato.
Flowers can attach to stems at widened spots {receptacle}.
Flowers have sepal concentric circles {calyx}|.
Flowers have calyx of outside leaflets {sepal}|.
Flowers have flowery leaves {petal}|.
Flowers have anthers on structures {stamen}|.
Flowers can have male sex organs {anther}| {antheridia} to make male sex cells, which make pollen sacs on stamens.
Anther sacs {microsporangia} develop male sex cells into microspores.
Microsporangia develop male sex cells into four spores {microspore}. Two microspores are tube nuclei. Two microspores are generative nuclei. One tube nucleus and one generative nucleus make one pollen grain, so process makes two pollen grains.
One tube nucleus and one generative nucleus make one grain {pollen grain} {pollen}|. Pollen grains leave stamens to try to land on stigmas.
Flowers have center structures {pistil, flower}|. Pistils have ovaries, styles, and stigmas.
Pistils have top parts {stigma, flower}|.
Pistils have middle parts {style, flower}.
Pistils have egg-making organs {carpel, flower}|, in which ovules develop.
Carpels have female sex cells {ovule}. Ovules develop to make eight nuclei, of which one becomes egg nucleus, two become polar nuclei, three are generative nuclei, and two form tube nuclei.
Ovules develop to make sacs {megasporangium}, with female spores {megaspore}.
Flowers have female sex organs {archegonia}.
Spermatophytes produce male microspores and female megaspores. Male pollen must transfer from anther to stigma, by wind {wind-pollinated flower} or by insect, animal, or bird pollinators {pollinator-pollinated flower}. Wind-pollinated flowers do not have fancy flowers or nectar. Spermatophytes transport pollen down pollen tubes to megaspores and unite gametes {pollination}|, to make fertilized embryos. Seeds have one embryo surrounded by endosperm, surrounded by epidermis. Seeds are transportable units.
Female ovules develop to make eight nuclei, of which two {tube nuclei} form tubes. After pollen grains land on stigmas, ovule and pollen tube nuclei form tubes down through styles to ovules.
Female ovules develop to make eight nuclei, of which three {generative nucleus} participate in fertilization. One generative nucleus divides. Second generative nucleus enters egg nucleus. Female-ovule polar nuclei and third generative nucleus fuse to make endosperm nucleus. Ovule and pollen generative nuclei make embryo {double fertilization}.
Female ovules develop to make eight nuclei, of which two {polar nucleus} become pole markers. Polar nuclei and third generative nucleus fuse to make endosperm nucleus.
Pollination makes fertilized gametes {embryo, plant}.
Ovule polar nuclei and third generative nucleus combine to make a nucleus {endosperm nucleus}.
Seeds have nutrient layers {endosperm} that surround embryos and have epidermis coverings. Endosperm nucleus makes endosperm.
After double fertilization, flowers fall off. Ovules thicken walls to form seeds. Ovaries enlarge to make new organs {fruit}|.
Fruits are mature-ovule seeds and ovary walls {pericarp}. Ovary walls can be fleshy, as in apple, or dry and hard, as in maple. Seeds can be in ovary, as in apples, peaches, oranges, squash, and cucumbers. Seeds can be on surface, as in corn and strawberry. Fleshy fruits can have one or more seeds and skin, as tomato, cranberry, banana, and grape. Compound inferior ovaries can have many seeds in thick flesh {pome}, as in pear and apple.
botanical fruit
Tomato, squash, cucumber, and eggplant {botanical fruit} develop from flowers and so are not like vegetables.
dehiscent
Some fruits do not split open to release seed {indehiscent} and are typically samaras. Dry fruits can have one seed that splits open {dehiscent}, as in walnut.
Sepals, petals, or receptacles can be fruit parts {accessory fruit}, as in apple. Accessory fruits {aggregate-accessory fruit} can have edible enlarged receptacles, as in strawberry and blackberry.
Fruits {aggregate fruit} can have simple flowers, with one corolla, one calyx, one stem, and many ovaries. Aggregate fruits can be from flowers with several pistils, as in raspberry and blackberry.
Fleshy fruits {berry, fruit}| can have pulpy walls.
Fruits {drupe}| can have stones, as in peach and apricot. One-seed fleshy fruits can have fleshy outer pericarp and bony inner pericarp {endocarp}.
Seeds can join to stalks {hilum}.
Fruit clusters can unite {multiple fruit}, as in pineapple. Multiple fruits have separate and independent flower clusters, with calyx and corolla, as in pineapple, fig, and beet.
Dry fruits {nut}| have shells.
Seeds {samara}| can have wings, as in ash, elm, and maple.
Fruits {simple fruit} can be from flowers with one pistil, such as cherry, date, and palm. Dry simple fruits have paper, leather, or hard ovary walls. Pods can split into two sides {valve, pod} with seeds attached to one edge, as in peanut, pea, bean, and other legumes. Dry thin-walled fruits or pods {capsule, fruit} can have more than one seed and several parts separated by grooved lines {carpel, fruit}, as in poppy.
Mature fertilized ovules {seed, plant}| have immature plants {embryo, seed}; protein, carbohydrate, or fat food supply {endosperm layer}, except in orchid; and soft inner linings {micropyle} or hard outer coverings {seed coat} to prevent water from entering seeds early. Seeds can remain dormant, if they have thick coats, low water, and starches for food.
Angiosperms {monocot}| {monocotyledon} can have one embryo seed leaf, one straight leaf vein, flower parts in threes, and xylem throughout.
Angiosperms {dicot}| {dicotyledon} can have two embryo seed leaves, branching leaf veins, flower parts in fours or fives, and xylem in rings or stem center.
Warmth, moisture, and oxygen start seed growth {germination}|.
First, a filament {suspensor} of cells grows. At suspensor end, one cell divides to make embryo, as a round cell mass. Embryo then makes cotyledon.
Embryos make primary seed leaves {cotyledon}|, which have a central axis. Angiosperms are monocotyledons or dicotyledons. Seed leaves enclose embryo but are not like mature leaves.
Axis above seed leaves {epicotyl} becomes stem and leaves.
Axes {hypocotyl} can be below seed leaves, be beside radicle, and have immature stems.
Immature leaves {plumule} can be beside hypocotyl.
After seeds absorb water, axis {radicle} below hypocotyl grows and emerges from seed to make primary root. Root grows down, pulling axis and cotyledon out of seed coat.
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Date Modified: 2022.0225