Editing Cactus (section)

==Reproductive ecology==
[[File:Schlumbergera 06 ies trimmed.jpg|thumb|Flower of ''[[Schlumbergera]]'' cut in half, showing typical adaptations to [[bird pollination]]|alt=Flower cut in half vertically with the base to the left; the bases of the tepals form a kind of tube, the upper parts bending away from the tube; the stamens run the full length of the flower from left to right and emerge from the end; some start at the very base of the flower, others start from further along to the right, being joined to a tepal.]]
[[File:Saguaroflowers.jpg|thumb|Flowers of [[saguaro]] showing flattish white flowers adapted for bat pollination]]
Cactus flowers are [[Pollination|pollinated]] by insects, birds and bats. None are known to be wind-pollinated and self-pollination occurs in only a very few species; for example the flowers of some species of ''[[Frailea]]'' do not open ([[cleistogamy]]).{{sfnp|Anderson|2001|p=33}} The need to attract [[pollinator]]s has led to the evolution of [[pollination syndrome]]s, which are defined as groups of "floral traits, including rewards, associated with the attraction and utilization of a specific group of animals as pollinators."{{sfnp|ps=none|Fenster|Armbruster|Wilson|Dudash|2004|p=376}}

[[Bee]]s are the most common pollinators of cacti; bee-pollination is considered to have been the first to evolve.{{sfnp|Anderson|2001|p=33}} Day-flying butterflies and nocturnal moths are associated with different pollination syndromes. Butterfly-pollinated flowers are usually brightly colored, opening during the day, whereas moth-pollinated flowers are often white or pale in color, opening only in the evening and at night.<ref name=HartNasoBhat02/> As an example, ''[[Lophocereus schottii]]'' is pollinated by a particular species of moth, ''[[Upiga virescens]]'', which also lays its eggs among the developing seeds its caterpillars later consume.<ref name=HartNasoBhat02/> The flowers of this cactus are funnel-shaped, white to deep pink, up to {{convert|4|cm|in|abbr=on|1}} long, and open at night.{{sfnp|Anderson|2001|p=537}}

[[Hummingbird]]s are significant pollinators of cacti. Species showing the typical hummingbird-pollination syndrome have flowers with colors towards the red end of the spectrum, anthers and stamens that protrude from the flower, and a shape that is not [[Floral symmetry|radially symmetrical]], with a lower lip that bends downwards; they produce large amounts of [[nectar]] with a relatively low sugar content.<ref name=FensArmbWilsDuda04/> ''[[Schlumbergera]]'' species, such as ''[[Schlumbergera truncata|S. truncata]]'', have flowers that correspond closely to this syndrome.{{sfnp|McMillan|Horobin|1995|p=49ff}} Other hummingbird-pollinated genera include ''[[Cleistocactus]]'' and ''[[Disocactus]]''.{{sfnp|Anderson|2001|p=33}}

Bat-pollination is relatively uncommon in flowering plants, but about a quarter of the genera of cacti are known to be pollinated by [[bat]]s—an unusually high proportion, exceeded among [[eudicots]] by only two other families, both with very few genera. Columnar cacti growing in semidesert areas are among those most likely to be bat-pollinated; this may be because bats are able to travel considerable distances, so are effective pollinators of plants growing widely separated from one another. The pollination syndrome associated with bats includes a tendency for flowers to open in the evening and at night, when bats are active. Other features include a relatively dull color, often white or green; a radially symmetrical shape, often tubular; a smell described as "musty"; and the production of a large amount of sugar-rich nectar. ''[[Saguaro|Carnegiea gigantea]]'' is an example of a bat-pollinated cactus, as are many species of ''[[Pachycereus]]'' and ''[[Pilosocereus]]''.<ref name=FlemGeisKres09/>

[[File:Schlumbergera fruit.png|thumb|Fruit of ''[[Schlumbergera]]'' cut in half; the length is 1.0~1.5&nbsp;cm.|alt=Green fruit of Schlumbergera cut in half, lying on a cutting board.]]
The [[fruit]]s produced by cacti after the flowers have been fertilized vary considerably; many are fleshy, although some are dry. All contain a large number of seeds. Fleshy, colorful and sweet-tasting fruits are associated with seed dispersal by birds. The seeds pass through their digestive systems and are deposited in their droppings. Fruit that falls to the ground may be eaten by other animals; [[Galápagos tortoise|giant tortoises]] are reported to distribute ''Opuntia'' seeds in the Galápagos Islands. [[Ant]]s appear to disperse the seeds of a few genera, such as ''[[Blossfeldia]]''. Drier spiny fruits may cling to the fur of mammals or be moved around by the wind.{{sfnp|Anderson|2001|pp=35–36}}