Petals are modified leaves that surround the reproductive parts of flowers. They are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are accompanied by another set of special leaves called sepals, that collectively form the calyx and lie just beneath the corolla; the calyx and the corolla together make up the perianth. When the petals and sepals of a flower are difficult to distinguish, they are collectively called tepals. Examples of plants in which the term tepal is appropriate include genera such as Tulipa. Conversely, genera such as Rosa and Phaseolus have well-distinguished petals; when the undifferentiated tepals resemble petals, they are referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly coloured tepals. Since they include Liliales, an alternative name is lilioid monocots. Although petals are the most conspicuous parts of animal-pollinated flowers, wind-pollinated species, such as the grasses, either have small petals or lack them entirely.

The role of the corolla in plant evolution has been studied extensively since Charles Darwin postulated a theory of the origin of elongated corollae and corolla tubes. A corolla of separate petals, without fusion of individual segments, is apopetalous. If the petals are free from one another in the corolla, the plant is choripetalous. In the case of fused tepals, the term is syntepalous; the corolla in some plants forms a tube. Petals can differ in different species; the number of petals in a flower may hold clues to a plant's classification. For example, flowers on eudicots most have four or five petals while flowers on monocots have three or six petals, although there are many exceptions to this rule; the petal whorl or corolla may be bilaterally symmetrical. If all of the petals are identical in size and shape, the flower is said to be regular or actinomorphic. Many flowers are termed irregular or zygomorphic. In irregular flowers, other floral parts may be modified from the regular form, but the petals show the greatest deviation from radial symmetry.

Examples of zygomorphic flowers may be seen in members of the pea family. In many plants of the aster family such as the sunflower, Helianthus annuus, the circumference of the flower head is composed of ray florets; each ray floret is anatomically an individual flower with a single large petal. Florets in the centre of the disc have no or reduced petals. In some plants such as Narcissus the lower part of the petals or tepals are fused to form a floral cup above the ovary, from which the petals proper extend. Petal consists of two parts: the upper, broad part, similar to leaf blade called the blade and the lower part, similar to leaf petiole, called the claw, separated from each other at the limb. Claws are developed in petals of some flowers such as Erysimum cheiri; the inception and further development of petals shows a great variety of patterns. Petals of different species of plants vary in colour or colour pattern, both in visible light and in ultraviolet; such patterns function as guides to pollinators, are variously known as nectar guides, pollen guides, floral guides.

The genetics behind the formation of petals, in accordance with the ABC model of flower development, are that sepals, petals and carpels are modified versions of each other. It appears that the mechanisms to form petals evolved few times, rather than evolving from stamens. Pollination is an important step in the sexual reproduction of higher plants. Pollen is produced by the male organs of hermaphroditic flowers. Pollen does not move on its own and thus requires wind or animal pollinators to disperse the pollen to the stigma of the same or nearby flowers. However, pollinators are rather selective in determining the flowers; this develops competition between flowers and as a result flowers must provide incentives to appeal to pollinators. Petals play a major role in competing to attract pollinators. Henceforth pollination dispersal could occur and the survival of many species of flowers could prolong. Petals have various purposes depending on the type of plant. In general, petals operate to protect some parts of the flower and attract/repel specific pollinators.

This is where the positioning of the flower petals are located on the flower is the corolla e.g. the buttercup having shiny yellow flower petals which contain guidelines amongst the petals in aiding the pollinator towards the nectar. Pollinators have the ability to determine specific flowers. Using incentives flowers draw pollinators and set up a mutual relation between each other in which case the pollinators will remember to always guard and pollinate these flowers; the petals could produce different scents to allure desirable pollinators or repel undesirable pollinators. Some flowers will mimic the scents produced by materials such as decaying meat, to attract pollinators to them. Various colour traits are used by different petals that could attract pollinators that have poor smelling abilities, or that only come out at certain parts of the day. Som

The Ephraim Hammond House known as Cedar Hill, is a historic house at 265 Beaver Street in Waltham, Massachusetts. The two story wood frame house was built in 1775, is Waltham's only side-hall Georgian house, it was added to the National Register of Historic Places in 1989. In the 19th century it became part of the Cedar Hill estate of Cornelia Lyman Warren, after which it was donated to the Massachusetts council of the Girl Scouts of the USA in the early 20th century; the house was restored under the auspices of the Girl Scouts and Helen Storrow, an early leader of the girls' scouting movement, serves as one of the council's service centers. Jonathan Hammond House National Register of Historic Places listings in Waltham, Massachusetts

Minor League Baseball is a hierarchy of professional baseball leagues in the Americas that compete at levels below Major League Baseball and provide opportunities for player development and a way to prepare for the major leagues. All of the minor leagues are operated as independent businesses. Most are members of the umbrella organization formally known as National Association of Professional Baseball Leagues, which operates under the Commissioner of Baseball within the scope of organized baseball. Several leagues, known as independent baseball leagues, do not have any official links to Major League Baseball. Except for the Mexican League, teams in the organized minor leagues are independently owned and operated but are directly affiliated with one major league team through a standardized Player Development Contract; these leagues go by the nicknames the "farm system", "farm club", or "farm team" because of a joke passed around by major league players in the 1930s when St. Louis Cardinals general manager Branch Rickey formalized the system, teams in small towns were "growing players down on the farm like corn".

Major League Baseball and Minor League Baseball teams may enter into a PDC for a two- or four-year term. At the expiration of a PDC term, teams may renew their affiliation, or sign new PDCs with different clubs, though many relationships are renewed and endure for extended time periods. For example, the Omaha Storm Chasers have been the Triple-A affiliate of the Kansas City Royals since the Royals joined the American League in 1969, but the Columbus Clippers changed affiliations, after being associated with the New York Yankees from 1979, to the Washington Nationals in 2007, have been affiliated with the Cleveland Indians since 2009. A few minor league teams are directly owned by their major league parent club, such as the Springfield Cardinals, owned by the St. Louis Cardinals, all of the Atlanta Braves' affiliates except the Florida Fire Frogs. Minor League teams that are owned directly by the major league club do not have PDCs with the parent club and are not part of the reaffiliation shuffles that occur after each even-numbered season.

Today, there are 14 MLB-affiliated minor leagues with a total of 160 revenue-generating teams, located in large and small cities and suburbs across the United States and Canada, there are three MLB-affiliated rookie leagues with a total of 80 teams, located in Arizona and the Dominican Republic, though these teams do not generate revenue. The earliest professional baseball league, the National Association of Professional Base Ball Players of 1871 to 1875, comprised all professional teams; this system proved unworkable, however, as there was no way to ensure competitive balance, financially unsound clubs failed in midseason. This problem was solved in 1876 with the formation of the National League, with a limited membership which excluded less competitive and financially weaker teams. Professional clubs outside the NL responded by forming regional associations of their own. There was a series of ad hoc groupings, such as the New England Association of 1877 and the Eastern Championship Association of 1881.

These were loose groups of independent clubs which agreed to play a series of games over the course of one season for a championship pennant. The first true minor league is traditionally considered to be the Northwestern League of 1883 to 1884. Unlike the earlier minor associations, it was conceived as a permanent organization, it along with the NL and the American Association, was a party to the National Agreement of 1883. Included in this was the agreement to respect the reserve lists of clubs in each league. Teams in the NL and the AA could only reserve players, paid at least $1000. Northwest League teams could reserve players paid $750, implicitly establishing the division into major and minor leagues. Over the next two decades, more minor leagues signed various versions of the National Agreement; the minor leagues joined together to negotiate jointly. In the late 1890s, the Western League run by Ban Johnson decided to challenge the NL's position. In 1900, he changed the name of the league to the American League and vowed to make deals to sign contracts with players who were dissatisfied with the pay and terms of their deals with the NL.

This led to a turf war that heated up in 1901 enough to concern Patrick T. Powers, president of the Eastern League, many other minor league owners about the conflict affecting their organizations. Representatives of the different minor leagues met at the Leland Hotel in Chicago on September 5, 1901. In response to the NL–AL battle, they agreed to form the National Association of Professional Baseball Leagues, called the NAPBL, or NA for short; the purpose of the NAPBL at the time was to maintain the independence of the leagues involved. Several continued to work independently. Powers was made the first president of the NAPBL, whose offices were established in Auburn, New York. In 1903, the conflict between the AL and NL ended in the National Agreement of 1903; the NAPBL became involved in the stages of the negotiations to develop rules for the acquisition of players from their leagues by the NL and the AL. The 1903 agreement ensured that teams would be compensated for the players that they had taken the time and effort to scout and develop, no NA team was required to sell their players, although most did because the cash was an important source of revenue for most teams.

The NA leagues were still fiercely independent, the term "minor" was used in reference to them, save by the m