Pollination is the transfer of pollen from a male part of a plant to a female part of a plant enabling fertilisation and the production of seeds, most by an animal or by wind. Pollinating agents are animals such as insects and bats. Pollination occurs within a species; when pollination occurs between species it can produce hybrid offspring in nature and in plant breeding work. In angiosperms, after the pollen grain has landed on the stigma, it develops a pollen tube which grows down the style until it reaches an ovary. Sperm cells from the pollen grain move along the pollen tube, enter an ovum cell through the micropyle and fertilise it, resulting in the production of a seed. A successful angiosperm pollen grain containing the male gametes is transported to the stigma, where it germinates and its pollen tube grows down the style to the ovary, its two gametes travel down the tube to where the gametophyte containing the female gametes are held within the carpel. One nucleus fuses with the polar bodies to produce the endosperm tissues, the other with the ovule to produce the embryo Hence the term: "double fertilization".
In gymnosperms, the ovule is not contained in a carpel, but exposed on the surface of a dedicated support organ, such as the scale of a cone, so that the penetration of carpel tissue is unnecessary. Details of the process vary according to the division of gymnosperms in question. Two main modes of fertilization are found in gymnosperms. Cycads and Ginkgo have motile sperm that swim directly to the egg inside the ovule, whereas conifers and gnetophytes have sperm that are unable to swim but are conveyed to the egg along a pollen tube; the study of pollination brings together many disciplines, such as botany, horticulture and ecology. The pollination process as an interaction between flower and pollen vector was first addressed in the 18th century by Christian Konrad Sprengel, it is important in horticulture and agriculture, because fruiting is dependent on fertilization: the result of pollination. The study of pollination by insects is known as anthecology. Pollen germination has three stages; the pollen grain is dehydrated so that its mass is reduced enabling it to be more transported from flower to flower.
Germination only takes place after rehydration, ensuring that premature germination does not take place in the anther. Hydration allows the plasma membrane of the pollen grain to reform into its normal bilayer organization providing an effective osmotic membrane. Activation involves the development of actin filaments throughout the cytoplasm of the cell, which become concentrated at the point from which the pollen tube will emerge. Hydration and activation continue. In conifers, the reproductive structures are borne on cones; the cones are either pollen cones or ovulate cones, but some species are monoecious and others dioecious. A pollen cone contains hundreds of microsporangia carried on reproductive structures called sporophylls. Spore mother cells in the microsporangia divide by meiosis to form haploid microspores that develop further by two mitotic divisions into immature male gametophytes; the four resulting cells consist of a large tube cell that forms the pollen tube, a generative cell that will produce two sperm by mitosis, two prothallial cells that degenerate.
These cells comprise a reduced microgametophyte, contained within the resistant wall of the pollen grain. The pollen grains are dispersed by the wind to the female, ovulate cone, made up of many overlapping scales, each protecting two ovules, each of which consists of a megasporangium wrapped in two layers of tissue, the integument and the cupule, that were derived from modified branches of ancestral gymnosperms; when a pollen grain lands close enough to the tip of an ovule, it is drawn in through the micropyle by means of a drop of liquid known as a pollination drop. The pollen enters a pollen chamber close to the nucellus, there it may wait for a year before it germinates and forms a pollen tube that grows through the wall of the megasporangium where fertilisation takes place. During this time, the megaspore mother cell divides by meiosis to form four haploid cells, three of which degenerate; the surviving one develops as a megaspore and divides to form an immature female gametophyte. Two or three archegonia containing an egg develop inside the gametophyte.
Meanwhile, in the spring of the second year two sperm cells are produced by mitosis of the body cell of the male gametophyte. The pollen tube elongates and pierces and grows through the megasporangium wall and delivers the sperm cells to the female gametophyte inside. Fertilisation takes place when the nucleus of one of the sperm cells enters the egg cell in the megagametophyte’s archegonium. In flowering plants, the anthers of the flower produce microspores by meiosis; these undergo mitosis to form male gametophytes. Meanwhile, the ovules produce megaspores by meiosis, further division of these form the female gametophytes, which are strongly reduced, each consisting only of a few cells, one of, the egg; when a pollen grain adheres to the stigma of a carpel it germinates, developing a pollen tube that grows through the tissues of the style, entering the ovule through the micropyle. When the tube reaches the egg sac, two sperm cells pass through it into the female gametophyte and fertil
In botany, an evergreen is a plant that has leaves throughout the year that are always green. This is true if the plant retains its foliage only in warm climates, contrasts with deciduous plants, which lose their foliage during the winter or dry season. There are many different kinds of both trees and shrubs. Evergreens include: most species of conifers, but not all live oak, "ancient" gymnosperms such as cycads most angiosperms from frost-free climates, such as eucalypts and rainforest trees clubmosses and relativesThe Latin binomial term sempervirens, meaning "always green", refers to the evergreen nature of the plant, for instance Cupressus sempervirens Lonicera sempervirens Sequoia sempervirens Leaf persistence in evergreen plants varies from a few months to several decades. Deciduous trees shed their leaves as an adaptation to a cold or dry/wet season. Evergreen trees do lose leaves, but each tree loses its leaves and not all at once. Most tropical rainforest plants are considered to be evergreens, replacing their leaves throughout the year as the leaves age and fall, whereas species growing in seasonally arid climates may be either evergreen or deciduous.
Most warm temperate climate plants are evergreen. In cool temperate climates, fewer plants are evergreen, with a predominance of conifers, as few evergreen broadleaf plants can tolerate severe cold below about −26 °C. In areas where there is a reason for being deciduous, e.g. a cold season or dry season, being evergreen is an adaptation to low nutrient levels. Deciduous trees lose nutrients. In warmer areas, species such as some pines and cypresses grow on disturbed ground. In Rhododendron, a genus with many broadleaf evergreens, several species grow in mature forests but are found on acidic soil where the nutrients are less available to plants. In taiga or boreal forests, it is too cold for the organic matter in the soil to decay so the nutrients in the soil are less available to plants, thus favouring evergreens. In temperate climates, evergreens can reinforce their own survival; these conditions favour the growth of more evergreens and make it more difficult for deciduous plants to persist.
In addition, the shelter provided by existing evergreen plants can make it easier for younger evergreen plants to survive cold and/or drought. Semi-deciduous Helen Ingersoll. "Evergreens". Encyclopedia Americana
Artemis, in the ancient Greek religion and myth, is the goddess of the hunt, the wilderness, wild animals, the Moon, chastity. Artemis is the daughter of Zeus and Leto, the twin sister of Apollo, she was the patron and protector of young girls, was believed to bring disease upon women and relieve them of it. Artemis was worshipped as one of the primary goddesses of childbirth and midwifery along with Eileithyia. Much like Athena and Hestia, Artemis is sworn never to marry. Artemis was one of the most venerated of the Ancient Greek deities and her temple at Ephesus was one of the Seven Wonders of the Ancient World. Artemis' symbols included a bow and arrow, a quiver and hunting knives and the deer and the cypress were sacred to her; the goddess Diana is her Roman equivalent. The name Artemis is of uncertain etymology, although various sources have been proposed. According to J. T. Jablonski, the name is Phrygian and could be "compared with the royal appellation Artemas of Xenophon. According to Charles Anthon the primitive root of the name is of Persian origin from *arta, *art, *arte, all meaning "great, holy," thus Artemis "becomes identical with the great mother of Nature as she was worshipped at Ephesus".
Anton Goebel "suggests the root στρατ or ῥατ, "to shake," and makes Artemis mean the thrower of the dart or the shooter". The name may be related to Greek árktos "bear", supported by the bear cult the goddess had in Attica and the Neolithic remains at the Arkoudiotissa Cave, as well as the story of Callisto, about Artemis, it is believed that a precursor of Artemis was worshipped in Minoan Crete as the goddess of mountains and hunting, Britomartis. While connection with Anatolian names has been suggested, the earliest attested forms of the name Artemis are the Mycenaean Greek, a-te-mi-to /Artemitos/ and, a-ti-mi-te /Artimitei/, written in Linear B at Pylos. R. S. P. Beekes suggested. Artemis was venerated in Lydia as Artimus. Georgios Babiniotis, while accepting that the etymology is unknown states that the name is attested in Mycenean Greek and is of Pre-Greek origin. Ancient Greek writers, by way of folk etymology, some modern scholars, have linked Artemis to ἄρταμος, artamos, i.e. "butcher" or, like Plato did in Cratylus, to ἀρτεμής, artemḗs, i.e. "safe", "unharmed", "uninjured", "pure", "the stainless maiden".
Various conflicting accounts are given in Classical Greek mythology regarding the birth of Artemis and Apollo, her twin brother. However, in terms of parentage, all accounts agree that she was the daughter of Zeus and Leto and that she was the twin sister of Apollo. An account by Callimachus has it that Hera forbade Leto to give birth on either terra firma or on an island. Hera was angry with her husband Zeus because he had impregnated Leto but the island of Delos disobeyed Hera and Leto gave birth there. According to the Homeric Hymn to Artemis the island where Leto gave birth was Ortygia. In ancient Cretan history Leto was worshipped at Phaistos and, in Cretan mythology, Leto gave birth to Apollo and Artemis on the islands known today as Paximadia. A scholium of Servius on Aeneid iii. 72 accounts for the island's archaic name Ortygia by asserting that Zeus transformed Leto into a quail in order to prevent Hera from finding out about his infidelity, Kenneth McLeish suggested further that in quail form Leto would have given birth with as few birth-pains as a mother quail suffers when it lays an egg.
The myths differ as to whether Artemis was born first, or Apollo. Most stories depict Artemis as born first, becoming her mother's midwife upon the birth of her brother Apollo; the childhood of Artemis is not related in any surviving myth. The Iliad reduced the figure of the dread goddess to that of a girl, having been thrashed by Hera, climbs weeping into the lap of Zeus. A poem by Callimachus to the goddess "who amuses herself on mountains with archery" imagines some charming vignettes. Artemis, while sitting on the knee of her father, asked him to grant her several wishes: to always remain a virgin to have many names to set her apart from her brother Phoebus to have a bow and arrow made by the Cyclops to be the Phaesporia or Light Bringer to have a knee-length tunic so that she could hunt to have sixty "daughters of Okeanos", all nine years of age, to be her choir to have twenty Amnisides Nymphs as handmaidens to watch her dogs and bow while she rested to rule all the mountains any city to have the ability to help women in the pains of childbirth.
Artemis believed that she had been chosen by the Fates to be a midwife since she had assisted her mother in the delivery of her twin brother, Apollo. All of her companions remained virgins, Artemis guarded her own chastity, her symbols included the golden bow and arrow, the hunting dog, the stag, the Moon. Callimachus tells how Artemis spent her girlhood seeking out the things that she would need to be a huntress, how she obtained her bow and arrows from the isle of Lipara, where Hephaestus and the Cyclops worked. Oceanus' daughters were filled with fear, but the young Artemis bravely approached and asked for bow and arrows. Callimachus tells how Artemis visited Pan, the god of the forest, who gave her seven bitches and six dogs, she captured six golden-horned deer to pull her chariot. Artemis practiced with h
Cupressus guadalupensis, the Guadalupe cypress, is a species of cypress from Guadalupe Island in the Pacific Ocean off western North America. The Guadalupe cypress, Cupressus guadalupensis, is endemic to Mexico, found only on Guadalupe Island in the Pacific Ocean west of Baja California, it is found growing at altitudes of 800–1,280 metres, in the island's recovering chaparral and woodlands habitats. Cupressus guadalupensis has been listed as being the same species as Cupressus forbesii, listed as a variety of C. guadalupensis in the past. Recent analysis, has placed C. forbesii as a separate, albeit related, species. Cupressus guadalupensis is an evergreen conifer tree with a conic to ovoid-conic crown, variable in size, with mature trees reaching 10–20 metres tall; the foliage grows in dense sprays, dark green to gray-green in color. The leaves are scale-like, 2–5 mm long, produced on rounded shoots; the seed cones are spherical to oblong, 12–35 mm long, with 6 to 10 scales, green at first, maturing gray-brown to gray about 20–24 months after pollination.
The cones remain closed for many years, only opening after the parent tree is killed in a wildfire, thereby allowing the seeds to colonise the bare ground exposed by the fire. The male cones are 3–5 mm long, release pollen in February–March. A specimen survived at Cistus Nursery outside of Portland, OR during the winter of 2013-14, where temperatures went to -11.1111 Celsius. Guadalupe Island had a population of numerous but old and weak trees in 2000; as a viable conifer woodland species they disappeared from the late 19th century onwards, as hordes of introduced feral goats ate the seedlings that germinated for over a century. One major subpopulation was destroyed and the isolated stands were nearly destroyed. With the animals destroying most vegetation, the island's cloud forest, the water table dropped, further jeopardizing the remaining two main subpopulations; the principal habitats were fenced in by 2001, long-awaited removal of goats was completed by 2005. The first young plants in 150 years or so are now able to mature without being grazed away.
The present small population of 100 extant trees are vulnerable to long term viability. It appears this cypress is more vulnerable to drought than other island native plants, such as the Guadalupe variety of Monterey Pine, so the population could decline further with future climate changes. Habitat and watershed restoration and support projects are ongoing by Mexican conservation organization programs. Cupressus guadalupensis is considered a vulnerable species by the IUCN. Conifer Specialist Group. "Cupressus guadalupensis". IUCN Red List of Threatened Species. Version 2006. International Union for Conservation of Nature. Retrieved 11 May 2006. Junak, S.. A.: Recent conservation efforts and current status of the flora of Guadalupe Island, Baja California, Mexico. Presentation at Taller sobre la Restauración y Conservación de Isla Guadalupe. Instituto Nacional de Ecología, November 13–14, 2003. HTML abstract. León de la Luz, José Luis. Biodiversity and Conservation 12: 1073–1082. Doi:10.1023/A:1022854211166 Little, D.
P.. Evolution and circumscription of the true Cypresses. Syst. Bot. 31: 461-480. Media related to Cupressus guadalupensis at Wikimedia Commons Gymnosperm Database: C. guadalupensis var. guadalupensis Gymnosperm Database: C. guadalupensis var. forbesii
Cupressus duclouxiana, known as the Chinese cypress or Yunnan cypress, is a species of conifer in the cypress family, Cupressaceae. It is endemic to China, where it is known from Sichuan, it grows in deep river gorges. Its habitat is mountain forest where it occurs alongside the Sikang pine and various oaks and chestnuts. Most old-growth stands of this tree have been cut down, it is still threatened by logging in many areas
Cupressus atlantica, the Moroccan cypress, is a rare coniferous tree endemic to the valley of the Oued n'Fiss river in the High Atlas Mountains south of Marrakech in western Morocco. The majority are old, with little regeneration due to overgrazing by goats; this species is distinct from the allied Cupressus sempervirens in its much bluer foliage with a white resin spot on each leaf, the smaller shoots being flattened in a single plane. It has smaller, globose cones, only 1.5-2.5 cm long. Cupressus dupreziana is more similar, C. atlantica is treated as a variety of it by some authors. Moroccan cypress does not however share the unique reproductive system of male apomixis found in Saharan cypress. Gymnosperm Database: Cupressus atlantica
Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, between 50 and 67 species of junipers are distributed throughout the Northern Hemisphere, from the Arctic, south to tropical Africa, from Ziarat, east to eastern Tibet in the Old World, in the mountains of Central America; the highest-known juniper forest occurs at an altitude of 16,000 ft in southeastern Tibet and the northern Himalayas, creating one of the highest tree-lines on earth. Junipers vary in size and shape from tall trees, 20–40 m tall, to columnar or low-spreading shrubs with long, trailing branches, they are evergreen with needle-like and/or scale-like leaves. They can be either dioecious; the female seed cones are distinctive, with fleshy, fruit-like coalescing scales which fuse together to form a "berry"-like structure, 4–27 mm long, with one to 12 unwinged, hard-shelled seeds. In some species, these "berries" are red-brown or orange; the seed maturation time varies between species from 6 to 18 months after pollination.
The male cones are similar to those of other Cupressaceae, with six to 20 scales. In zones 7 through 10, junipers can release pollen several times each year. A few species of junipers bloom in autumn, while most species pollinate from early winter until late spring. Many junipers have two types of leaves; when juvenile foliage occurs on mature plants, it is most found on shaded shoots, with adult foliage in full sunlight. Leaves on fast-growing'whip' shoots are intermediate between juvenile and adult. In some species, all the foliage is with no scale leaves. In some of these, the needles are jointed at the base, in others, the needles merge smoothly with the stem, not jointed; the needle-leaves of junipers are hard and sharp, making the juvenile foliage prickly to handle. This can be a valuable identification feature in seedlings, as the otherwise similar juvenile foliage of cypresses and other related genera is soft and not prickly. Juniper is the exclusive food plant of the larvae of some Lepidoptera species, including Bucculatrix inusitata and juniper carpet, is eaten by the larvae of other Lepidoptera species such as Chionodes electella, Chionodes viduella, juniper pug, pine beauty.
Junipers are gymnosperms, which means they have no flowers or fruits. Depending on the species, the seeds they produce take 1 -- 3 years; the impermeable coat of the seed keeps water from getting in and protects the embryo when being dispersed. It can result in a long dormancy, broken by physically damaging the seed coat. Dispersal can occur from being swallowed whole by mammals; the resistance of the seed coat allows it to be passed down through the digestive system and out without being destroyed along the way. These seeds last a long time, as they can be dispersed long distances over the course of a few years; the number of juniper species is in dispute, with two recent studies giving different totals, Farjon accepting 52 species, Adams accepting 67 species. The junipers are divided into several sections, though which species belong to which sections is still far from clear, with research still on-going; the section Juniperus is an obvious monophyletic group though. Juniperus sect. Juniperus: Needle-leaf junipers.
The adult leaves are needle-like, in whorls of three, jointed at the base. Juniperus sect. Juniperus subsect. Juniperus: Cones with 3 separate seeds. Juniperus communis – Common juniper Juniperus communis subsp. Alpina – Alpine juniper Juniperus conferta – Shore juniper Juniperus rigida – Temple juniper or needle juniper Juniperus sect. Juniperus subsect. Oxycedrus: Cones with 3 separate seeds. Juniperus brevifolia – Azores juniper Juniperus cedrus – Canary Islands juniper Juniperus deltoides – Eastern prickly juniper Juniperus formosana – Chinese prickly juniper Juniperus lutchuensis – Ryukyu juniper Juniperus navicularis – Portuguese prickly juniper Juniperus oxycedrus – Western prickly juniper or cade juniper Juniperus macrocarpa – Large-berry juniper Juniperus sect. Juniperus subsect. Caryocedrus: Cones with 3 seeds fused together. Juniperus drupacea – Syrian juniperJuniperus sect. Sabina: Scale-leaf junipers; the adult leaves are scale-like, similar to those of Cupressus species, in opposite pairs or whorls of three, the juvenile needle-like leaves are not jointed at the base.
Provisionally, all the other junipers are included here. Old World species Juniperus chinensis – Chinese juniper Juniperus convallium – Mekong juniper Juniperus excelsa – Greek juniper Juniperus excelsa polycarpos – Persian juniper Juniperus foetidissima – Stinking juniper Juniperus indica – Black juniper Juniperus komarovii – Komarov's juniper Juniperus phoenicea – Phoenicean juniper Juniperus pingii – Ping juniper Juniperus procera – East African juniper Juniperus procumbens – Ibuki juniper Juniperu