Contains 55 Genera and 174 accepted taxa overall
Palms are any of the species of plants belonging to the taxonomic family Arecaceae. The family includes 200 genera and approximately 3,000 species. They are the fourth largest family of monocot plants. They are of the order Principes, "princes of the plant world". There are 6 subfamilies that hold 14 tribes, and 36 subtribes before classifying the genera. The different species can contrast greatly with each other in a variety of ways. The plant itself may look different or its fruit, leaves, stem, or flowers. There are many different factors that make each species unique. 
This group of woody shrubs, vines, or trees come in a variety of appearances.  They have a single trunk that does not normally branch out, although some bifurcate, split in two, numerously. Some are low to the ground while others grow tall. There are some palms that have stems which grow underground, but many are climbing stems. There are different types like those that only grow a few millimeters in diameter, those that are tall and cylindrical, and others that are swollen at the base or middle and get thinner. Many have leftover marks from old, fallen leaves that are rings or nodes on the stem. These are made from the bases of the leaves that adhere to the trunk, leaving behind scars as they fall. Unlike most trees these do not contain bark. They also do not develop true wood that have annual rings that can be seen when cut into. In the stems there are vascular bundles that are in soft tissue. This provides the organism with strength and flexibility enabling it to bend in the wind without breaking. 
The leaves in this family are some of the largest in the entire plant kingdom. The most distinct part is the crown of leaves. They are either palmate (fan-shaped), pinnate (feather-shaped), or bipinnate (wedge-shaped segments). The leaves are very much like the plant species themselves, they differ greatly when comparing sizes and shapes and segment divisions. Some of the palmate leaves are costapalmates because their petiole enter the balde of the leaf so that it looks like something between a palmate and a pinnate leaf. Leaflets can be found on the edges of the leaf stem on pinnate leaves. These leaflets are narrow or broad, linear or wedged. Most of them have a plumose look about them, but some do not divide at all and are oddly arranged. There are many different colors such as deep green, pale green, pale blue, silver, or burgundy. The leaves are normally deep-red or bronze when they first begin to grow. As the leaves mature, the colors will change. 
The leave's petiole (rachis) is stout, woody, and spine-like and envelops the stem. They form tubular pillars (crownshaft) and a lamina and then the entire leaf will split into rigid segments (pinnae). The folded pinnae are one of two shapes, induplicate (V-shaped) with the midrib protruding downward or reduplicate (upside-down V-shape) with the midrib protruding up. The inflorescences are racemosepanicles or spadix-like spikes that are protected by bracts of wood (spathes). They will form with the leaves and may be solitary or in multiples. Some are elongated organs and have curving flagellums that help the plant to climb onto vegetation that is close by. 
Palms have a particularly unique root system. Unlike most trees whose roots branch out underground, these generally do not. They have a numerous root system that stay bunched together at the base of the tree stem. As usuall most of the roots are located in the soil underneath the plant, but as it gets older new roots are formed. Some of these new roots sometimes begin to grow above the soil as either a stilt or prop roots. In many of those located in rainforests, the roots are near the surface and not deep underground. They are found beneath the humus on the forest floor. Those living in open forests or habitats with seasonal rainfall have roots that go down deep in order to anchor the plant well and find sufficient water supplies.
Palm flowers come in a vast array of appearances. They are small, sessile (having no stalk) or peduncular, and can be either solitary or clustered together. Usually they are inconspicuous and do not catch one's attention right away. Their color is generally a yellow-green shade. The female is more noticeable than the smaller sized male. There is also a large gap in numbers with males overpopulating the females. In this flower, there are 6 stamen that are grouped together in two separate whorls, 3 stamen in each whorl, each with biloculate anthers. There is also an ovary with 3 carpels, or 3 connate carpels.  These flowers are either unisexual or bisexual. There are 3 sexual forms of which palms will take that is monoecious, dioecious, or polygamous. Monoecious is when the male and female flowers are found on the same inflorescence or separated but still on the same plant. Dioecious is when male flowers and female flowers are on individual inflorescences that are on 2 different plants. Polygamous is when bisexual and unisexual flowers are combined in various ways on the same inflorescence. When unisexual flowers are not present, the group will be hermaphroditic and have bisexual flowers.
The seeds of palms can be either shaped as an ovoid (egg shaped), ellipsoid (solid ellipse), or globose (spherical). They are of a wide range of sizes, for example, one could be only a few millimeters in diameter and another could be almost half of a meter in diameter.  Each fruit contains 1-3 seeds. These seeds are filled with lipidic substances (fats and oils) and also with protein reserves. They can weigh as much as 20 kilograms, and are of the largest seeds ever. 
Pollination occurs mostly through the eating of the plant's fruits because many of their seeds are too large to be carried by the wind. The fruits appear on the plant as drupes (seeds with stony layer surrounded by flesh) or as berries. These fruits will differentiate exponentially in both stature and shape. The mesocarp makes up the fleshy part of the fruit but can also be dry or fibrous. The epicarp is either smooth or rugose (sulcate or covered in scales or spines). the endocarp is the membranous or woody portion of the fruit. 
Palms inhabit a wide variety of habitats in the world. They can be found in tropical forests, mangrove marshes, highland woods, and even deserts. There are many climatic factors that can affect this plants growth in different ways. The most important ones are factors such as: temperature, air humidity, water supply, sunlight, and the kind of substratum. For example, those living in tropical or subtropical regions live in high temperatures and high air humidity. These plants would be considered a major source of vegetation. They also hold an abundance of palms, more specifically, in tropical America which holds the most. Even though they live in many habitats, they have a low tolerance to cool climates and therefore do not grow in regions above 3,000m in altitude. They can be found in areas with monsoons or in xerophilous areas, many of them live in desert or semidesert regions. When they live in rainforests or highland woods, they will push upwards by using their spines on the stems in order to reach past the other plants to get to the sun. 
The 3 major types of soil that they prefer to grow in are sandy subtrata, high salinity levels or rocky substrata, and serpentine ones.  The majority of palms are located in tropical, moist regions of the world. On average, they must be exposed to about 20inches or more rainfall per year. The northernmost palm was found in Europe/North America around the Mediterranean Sea. The southernmost was found in New Zealand. While the vast majority of them live in many habitats, there are some species of palms that are confined to one island and can't grow anywhere else. 
Palms are important in human resources in multiple ways. They can be a source of food, fibers, ornamental, and other trinkets. Coconuts from the genus Cocos is from a tree that can grow in many areas and provides many with food. Other foods include dates and sago. Fibers can also be used such as copra and coir raffia and rattan fiber. Many useful things can also come from the oil palm. Vegetable oil, margarine, and soap are all examples of things that are made by this particular palm. They are also very popular in ornamental purposes. Many can be found as household plants. 
- Arecaceae wikipedia
- Arecaceae (Palmae) Dr. Gerald Carr
- Introduction to Palms Keith Boyer. Extracted from "Palms and Cycads Beyond the Tropics". PACSOA.
- The Palms Anna Guglielmo, Pietro Pavone, and Cristina Salmeri. PACSOA.
- Palm (plant) MSN Encarta Online Encyclopedia.