That tomatoes pollinate themselves poorly without outside aid is clearly shown in greenhouse situations where pollination must be aided by artificial wind, vibration of the plants (one brand of vibrator is a wand called an "electric bee" that is used manually), or more often today, by cultured bumblebees[citation needed]. The anther of a tomato flower is shaped like a hollow tube, with the pollen produced within the structure, rather than on the surface as in most species. The pollen moves through pores in the anther, but very little pollen is shed without some kind of outside motion. The best source of outside motion is a sonicating bee such as a bumblebee or the original wild halictid pollinator. In an outside setting, wind or animals provide sufficient motion to produce commercially viable crops.