From a Worcester Allotment: About Pumpkins

Pumpkins belong to the Melon (Curcurbita) family.
They are typically orange or yellow and have many creases running from the stem to the bottom.
They have a thick shell on the outside, with seeds and pulp on the inside.

Know your Pumpkins - Botany

Pumpkins generally weigh 9–18 lbs (4–8 kg) with the largest (of the species C. maxima) capable of reaching a weight of over 75 lbs (34 kg).
The pumpkin varies greatly in shape, ranging from oblate to oblong.
The rind is smooth and usually lightly ribbed.
Although pumpkins are usually orange or yellow, some fruits are dark green, pale green, orange-yellow, white, red and grey.
Pumpkins are monoecious, having both male and female flowers on the same plant.
The female flower is distinguished by the small ovary at the base of the petals.
These bright and colourful flowers have extremely short life spans and may only open for as short a time as one day.
The colour of pumpkins is derived from the orange pigments abundant in them.
The main nutrients are lutein and both alpha and beta carotene, the latter of which generates vitamin A in the body.

This group of primarily squash includes the pumpkins frequently used for commercially canned pumpkins.
Commercial pumpkin varieties usually have a tan-coloured skin.

These are the Jack-o-Lantern pumpkins you carve on Halloween, as well as the cute little miniature pumpkins that fit in the palm of your hand.
The traditional Jack O'Lantern is a particular variety officially known as the Connecticut Field Pumpkin.
Some of the most popular varieties include:

Maxima, as it's name implies, are the giant pumpkins.
Giant pumpkin growing has become a very popular hobby.
Giant pumpkin growers are among the most devoted, and perhaps fanatical of gardeners.
The uniqueness of this variety lies in its production of fruits more massive than those produced by any other plant in the world.
Fruit can exceed 6 feet (1.8 m) in diameter.
The heaviest Atlantic Giant on record weighed 1,810.5 pounds (821.2 kg) and was grown in Wisconsin in 2010.
Popular giant pumpkin varieties include:

Pumpkins are very versatile in their uses for cooking.
Most parts of the pumpkin are edible, including the fleshy shell, the seeds, the leaves, and even the flowers.
In the United States, pumpkin is a very popular Halloween and Thanksgiving staple.
Although most people use store-bought canned pumpkin, homemade pumpkin purée can serve the same purpose.