where can I find a list of all fruits we know of?

Answer 1

http://en.wikipedia.org/wiki/List_of_fruits

Answer 2

This was the tip of the iceberg:

Rosaceae family
The Family Rosaceae dominates the temperate fruits, both in numbers and in importance. The pome fruits, stone fruits and brambles are fruits of plants in Rosaceae.

The pome fruits:


ApplesApple and crabapple (Malus)
Chokeberry also called cooking apple (Aronia)
Hawthorn (Crataegus and Rhaphiolepis)
Serviceberry or saskatoon (Amelanchier)
Loquat (Eryobotrya japonica)
Medlar (Mespilus germanica)
Pear, European and Asian species (Pyrus)
Quince (Cydonia oblonga and Chaenomeles)
Rowan (Sorbus)
Service tree (Sorbus domestica), bears a fruit known as a sorb or sorb apple
Rose-hip, the fruitlike base of roses (Rosa); used mostly for jams and herbal tea
Shipova (× Sorbopyrus auricularis)
The stone fruits, drupes of genus Prunus:

Apricot (Prunus armeniaca or Armeniaca vulgaris)
Cherry, sweet, sour, and wild species (Prunus avium, P. cerasus, and others)
Chokecherry (Prunus virginiana)
Plum, of which there are several domestic and wild species; dried plums are called prunes
Peach (of the normal and white variety) and its variant the nectarine (Prunus persica)
Hybrids of the preceding species, such as the pluot, aprium and peacotum
Greengage, a cultivar of the plum

[edit] Berries
In non-technical usage, berry means any small fruit that can be eaten whole and lacks objectionable seeds. The bramble fruits, compound fruits of genus Rubus (blackberries), are some of the most popular pseudo-berries:


RaspberriesBlackberry, of which there are many species and hybrids, such as dewberry, boysenberry, olallieberry and loganberry (genus Rubus)
Raspberry, several species (genus Rubus)
Cloudberry (Rubus chamaemorus)
Wineberry (Rubus phoenicolasius)
Salmonberry (Rubus spectabilis)
Loganberry (Rubus loganobaccus)
Thimbleberry (Rubus parviflorus)
The true berries are dominated by the family Ericaceae, many of which are hardy in the subarctic:

Bearberry (Arctostaphylos spp.)
Bilberry or whortleberry (Vaccinium spp.)
Blueberry (Vaccinium spp.)
Crowberry (Empetrum spp.)
Cranberry (Vaccinium spp.)
Huckleberry (Vaccinium spp.)
Lingonberry (Vaccinium vitis-idaea)
Strawberry Tree (Arbutus unedo), not to be confused with the Strawberry (Fragaria)
Other berries not in the Rosaceae or Ericaceae:

Barberry (Berberis; Berberidaceae)
Currant (Ribes spp.; Grossulariaceae), red, black, and white types
Elderberry (Sambucus; Caprifoliaceae)
Gooseberry (Ribes spp.; Grossulariaceae)
Hackberry (Celtis spp.; Cannabaceae)
Honeysuckle: the berries of some species (called honeyberries) are edible, others are poisonous (Lonicera spp.; Caprifoliaceae)
Mayapple (Podophyllum spp.; Berberidaceae)
Nannyberry or sheepberry (Viburnum spp.; Caprifoliaceae)
Oregon grape (Mahonia aquifolium; Berberidaceae)
Sea-buckthorn (Hippophae rhamnoides; Elaeagnaceae)
Sea Grape (Coccoloba uvifera; Polygonaceae)
Wolfberry (Lycium barbarum, Lycium spp.; Solanaceae)
Mulberry (Morus spp.; Moraceae)