Flowering plant

Flowering plants
Temporal range: Early Cretaceous - present, 120–0  Ma
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Sweetbay Magnolia Magnolia virginiana Flower Closeup 2242px.jpg
Magnolia virginiana

sweet bay

Scientific classification
Kingdom: Plantae
Subkingdom: Embryophyta
(unranked): Spermatophyta
(unranked): Angiosperms
Groups (APG IV) [1]

Basal angiosperms

Core angiosperms

Synonyms

The flowering plants, also known as angiosperms, Angiospermae [5] [6] or Magnoliophyta, [7] are the most diverse group of land plants, with 416 families, approximately 13,164 known genera and c. 295,383 known species. [8] Like gymnosperms, angiosperms are seed-producing plants. However, they are distinguished from gymnosperms by characteristics including flowers, endosperm within the seeds, and the production of fruits that contain the seeds. Etymologically, angiosperm means a plant that produces seeds within an enclosure; in other words, a fruiting plant. The term comes from the Greek words angeion ("case" or "casing") and sperma ("seed").

The ancestors of flowering plants diverged from gymnosperms in the Triassic Period, 245 to 202 million years ago (mya), and the first flowering plants are known from 160 mya. They diversified extensively during the Lower Cretaceous, became widespread by 120 mya, and replaced conifers as the dominant trees from 100 to 60 mya.

Description

Angiosperm derived characteristics

Angiosperms differ from other seed plants in several ways, described in the table below. These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants and the most commercially important group to humans. [a]

Distinctive features of angiosperms
Feature Description
Flowering organs Flowers, the reproductive organs of flowering plants, are the most remarkable feature distinguishing them from the other seed plants. Flowers provided angiosperms with the means to have a more species-specific breeding system, and hence a way to evolve more readily into different species without the risk of crossing back with related species. Faster speciation enabled the Angiosperms to adapt to a wider range of ecological niches. This has allowed flowering plants to largely dominate terrestrial ecosystems.[ citation needed]
Stamens with two pairs of pollen sacs Stamens are much lighter than the corresponding organs of gymnosperms and have contributed to the diversification of angiosperms through time with adaptations to specialized pollination syndromes, such as particular pollinators. Stamens have also become modified through time to prevent self-fertilization, which has permitted further diversification, allowing angiosperms eventually to fill more niches.
Reduced male parts, three cells The male gametophyte in angiosperms is significantly reduced in size compared to those of gymnosperm seed plants.[ citation needed] The smaller size of the pollen reduces the amount of time between pollination — the pollen grain reaching the female plant — and fertilization. In gymnosperms, fertilization can occur up to a year after pollination, whereas in angiosperms, fertilization begins very soon after pollination. [9] The shorter amount of time between pollination and fertilization allows angiosperms to produce seeds earlier after pollination than gymnosperms, providing angiosperms a distinct evolutionary advantage.
Closed carpel enclosing the ovules (carpel or carpels and accessory parts may become the fruit) The closed carpel of angiosperms also allows adaptations to specialized pollination syndromes and controls. This helps to prevent self-fertilization, thereby maintaining increased diversity. Once the ovary is fertilized, the carpel and some surrounding tissues develop into a fruit. This fruit often serves as an attractant to seed-dispersing animals. The resulting cooperative relationship presents another advantage to angiosperms in the process of dispersal.
Reduced female gametophyte, seven cells with eight nuclei The reduced female gametophyte, like the reduced male gametophyte, may be an adaptation allowing for more rapid seed set, eventually leading to such flowering plant adaptations as annual herbaceous life-cycles, allowing the flowering plants to fill even more niches.
Endosperm In general, endosperm formation begins after fertilization and before the first division of the zygote. Endosperm is a highly nutritive tissue that can provide food for the developing embryo, the cotyledons, and sometimes the seedling when it first appears.

Vascular anatomy

Cross-section of a stem of the angiosperm flax:
1. Pith, 2. Protoxylem, 3. Xylem I, 4. Phloem I, 5. Sclerenchyma ( bast fibre), 6. Cortex, 7. Epidermis

The amount and complexity of tissue-formation in flowering plants exceeds that of gymnosperms. The vascular bundles of the stem are arranged such that the xylem and phloem form concentric rings.

In the dicotyledons, the bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue known as cambium. By the formation of a layer of cambium between the bundles (interfascicular cambium), a complete ring is formed, and a regular periodical increase in thickness results from the development of xylem on the inside and phloem on the outside. The soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Owing to differences in the character of the elements produced at the beginning and end of the season, the wood is marked out in transverse section into concentric rings, one for each season of growth, called annual rings.

Among the monocotyledons, the bundles are more numerous in the young stem and are scattered through the ground tissue. They contain no cambium and once formed the stem increases in diameter only in exceptional cases.

Reproductive anatomy

A collection of flowers forming an inflorescence

The characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, and provide the most trustworthy external characteristics for establishing relationships among angiosperm species. The function of the flower is to ensure fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally on a shoot or from the axil of a leaf (where the petiole attaches to the stem). Occasionally, as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. More typically, the flower-bearing portion of the plant is sharply distinguished from the foliage-bearing or vegetative portion, and forms a more or less elaborate branch-system called an inflorescence.

There are two kinds of reproductive cells produced by flowers. Microspores, which will divide to become pollen grains, are the "male" cells and are borne in the stamens (or microsporophylls). The "female" cells called megaspores, which will divide to become the egg cell ( megagametogenesis), are contained in the ovule and enclosed in the carpel (or megasporophyll).

The flower may consist only of these parts, as in willow, where each flower comprises only a few stamens or two carpels. Usually, other structures are present and serve to protect the sporophylls and to form an envelope attractive to pollinators. The individual members of these surrounding structures are known as sepals and petals (or tepals in flowers such as Magnolia where sepals and petals are not distinguishable from each other). The outer series (calyx of sepals) is usually green and leaf-like, and functions to protect the rest of the flower, especially the bud. The inner series (corolla of petals) is, in general, white or brightly colored, and is more delicate in structure. It functions to attract insect or bird pollinators. Attraction is effected by color, scent, and nectar, which may be secreted in some part of the flower. The characteristics that attract pollinators account for the popularity of flowers and flowering plants among humans.

While the majority of flowers are perfect or hermaphrodite (having both pollen and ovule producing parts in the same flower structure), flowering plants have developed numerous morphological and physiological mechanisms to reduce or prevent self-fertilization. Heteromorphic flowers have short carpels and long stamens, or vice versa, so animal pollinators cannot easily transfer pollen to the pistil (receptive part of the carpel). Homomorphic flowers may employ a biochemical (physiological) mechanism called self-incompatibility to discriminate between self and non-self pollen grains. In other species, the male and female parts are morphologically separated, developing on different flowers.

Other Languages
Afrikaans: Bedeksadiges
አማርኛ: ክንንብ ዘር
aragonés: Magnoliophyta
asturianu: Magnoliophyta
azərbaycanca: Çiçəkli bitkilər
Bân-lâm-gú: Khui-hoe si̍t-bu̍t
Basa Banyumasan: Tetanduran ngembang
беларуская: Кветкавыя
беларуская (тарашкевіца)‎: Кветкавыя расьліны
भोजपुरी: फूलदार पौधा
български: Покритосеменни
Boarisch: Bedecktsama
bosanski: Cvjetnica
čeština: Krytosemenné
Deutsch: Bedecktsamer
dolnoserbski: Pókšyty semjenjak
Ελληνικά: Αγγειόσπερμα
español: Angiospermae
Esperanto: Angiospermoj
français: Angiosperme
galego: Anxiospermas
한국어: 속씨식물
hornjoserbsce: Krytosymjenjak
Bahasa Indonesia: Tumbuhan berbunga
íslenska: Dulfrævingar
italiano: Magnoliophyta
Kreyòl ayisyen: Anjyospèm
Latina: Angiospermae
latviešu: Segsēkļi
Lëtzebuergesch: Bléieplanzen
lietuvių: Magnolijūnai
Limburgs: Bedèkzäöjige
lumbaart: Magnoliophyta
македонски: Скриеносеменици
മലയാളം: സപുഷ്പി
Bahasa Melayu: Angiosperma
Nāhuatl: Teconxinachtli
Nederlands: Bedektzadigen
日本語: 被子植物
Nordfriisk: Bloosenplaanten
norsk nynorsk: Dekkfrøplantar
occitan: Magnoliophyta
oʻzbekcha/ўзбекча: Gulli oʻsimliklar
Plattdüütsch: Todecktsadige
português: Angiosperma
română: Magnoliophyta
Runa Simi: Qatasqa muruyuq
sicilianu: Magnoliophyta
Simple English: Flowering plant
slovenščina: Kritosemenke
српски / srpski: Скривеносеменице
srpskohrvatski / српскохрватски: Skrivenosjemenice
svenska: Blomväxter
తెలుగు: ఆవృతబీజాలు
lea faka-Tonga: ʻakau matala
українська: Покритонасінні
vepsän kel’: Peitsemnižed
Tiếng Việt: Thực vật có hoa
West-Vlams: Bedektzoadign
粵語: 被子植物
žemaitėška: Žėidėnē augalā
中文: 被子植物