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}.
4-Botany-Plant-Vascular-Angiosperm
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Date Modified: 2022.0225