one sperm and one egg are brought together, forming a new signle diploid cell, the fertilized egg

in plants, the life cycle is more complex. the plants you are familiar with--trees, shrubs, and herbs--aare all just one phase of the plant life cycle.

always diploid, like most adult animals, and they have organs (located in the flowers in angiosperms) with cells capable of undergoing meiosis.

in animals, meiosis result in haploid gamestses, but in plants, its results in haploid

gametes can fuse with other gametes in a process; producign the diploid zygote. a gamete that does not undergo syngamy dies because it cannot live by itself and usually cannot grow into a new, haploid individual ( unfertilized eggs of some insects such as bees are exceptional develop into sterile workers).

plant spores are just the opposite: they cannot undergo syngamy,l but each undergoes mitosis and grows into an entire new haploid plant

a life cycle like this, with two generation--sporophyte and gametophyte

because gametophytes do not resemble sporophytes at allm, this is an alternation; this is a complex life cycle, with at least three distinct plants(one sporophytes and tow gametophytes).

the very end of the axis, where the other flowers parts are attached, is the receptacle

there are four types of floral appendages: sepals, petals, stamens, and carpels. most flowers have all fours types

it is not uncommon for flowers of certain species to lack one or two of the four basic floral appendages

the lowermost and outermost of ht efour floral appendages. they are modified leaves that surround and enclose the other flower parts as they mature.

above the sepals on the receptacle are the petals, which grow together making up the (corolla)*

where pollen is actually produced. as part of the sporophyte, the anther is composed of diploid cells, and in each cells enlarge and prepare for meiosis

continue to enlarge and then undergo meiosis, each producing four microspores.

microspores initially remain together in a tetrad, but later separate, expand to a characteristic shape, and form an especially resistant wall.

the female reproductive organ of a flower, consisting of an ovary, a stigma, and usually a style. It may occur singly or as one of a group.

usually they are fused together into a single compound structure, frequently called a pistil. inside the ovary

regions of tissue that bear small structures; have a short stalk, called a funiculus, hat carries water and nutrients from the placenta to the ovule by means of a small vascular bundle.

around the nucellus are two thin sheets of cells (integuments) that cover almost the entire nucellus surface, leaving only a small hole

in anthers, some nucellus cells, usually only noe in each ovule, enlarge in preparation for meiosis

the microscope nucleus migrates to the side of the pollen grain and lies next to the wall. there it divides mitotically

which subsequently divides and forms two sperm cells. the entire microgametophyte consists of the vegetative cell and the two sperm cells (the microgametes).

after a pollen grain lands on a stigma, it germinates by producing; that penertrates into the loose, open tissues of hte stigma. the pollen tube absorbs nutrients for the stigma and grows downward through the style toward the ovary.

the technical term for a multinucleate megagametophyte; the nuclei migrate through the cytoplasm, pulled by microtubules, until three nuclei lie at each end and two in th ecenter. walls then form around the nuclei, and the large, eight-nucleate megaspore becmoes a megagametophyte with seven cells,one of ehich is binucleate

the cell in the venter of the archegonium whose division produces the egg and usually also the ventral canal cell

either of the two nuclei of a seed plant embryo sac that are destined to form endosperm

the three haploid cells that remain at the non-micropylar end of the embryo sac subsequent to division of the cells. After the formation of the egg cell they play little or no further part in seed development

A group of three cells in the seven-celled embryo sac of an angiosperm (flowering plant) consisting of the egg cell and two associated cells called synergids.

like the microgametophyte, the megagametophyte is a distinct plant. as with the pollen, the megagametophyte obtains all of its nourishment form the parent sporophyte

fusion of the nuclei. as a pollen tube grows downward through the style toward the ovule, it is guided to the ovuel's micropyle by some means

in angiosperms only, the seond sperm nucleus releases form the pollen tube migreates form the synergid into th ecentral cell. in undergoes karyogamy with both polar nuclei,

because both sperm nuclei undergo fusions-one with the egg nucleus and the other with the polar nuclei

which pushes the embryo deep into the endosperm. usually delicate and ephemeral in angiosperms; it is crushed by the later growth of the embryo and is not easily detectable in a mature seed.

the end of the embryo father form the suspensor initiates two primordia that grow into two cotyledons in basal angiosperms adn eudicots.

the part of a plant embryo that develops into the primary root

the part of the stem of an embryo plant beneath the stalks of the seed leaves or cotyledons and directly above the root.

the integuments that surround the nucellus expand and matures; as the rest of the ovule grows. in their last stages of maturation, they may becomes quite sclerenchymatous and tough.

as the ovule develops into a seed, the ovary matures into a fruit. development varies with the nature of the carpels as well as the nature of the mature fruit.

relative thickness and fleshiness of these layers vary with fruit type, and often one or two layers are absent. the entire fruit wall, whether composed of one, two, or all three layers

pollination of a carpel by pollen from the same flower or another flower on the same plant. in any plant population, there is genetic diversity.

in many species, especially many important crop species, self-pollination is inhibited

among incomplete flowers there is a significant difference between flowers that lack sepals or petals stamens or carpels.