Table 1.

Apparent functions of simple trichomes, GSTs and hydathode trichomes

Apparent functions	Trichome type*	Reference
Reduced insect movement	ST and GST	Levin, 1973; Johnson, 1975; Kessler, 2002; Kennedy, 2003
Temperature regulation	ST and GST	Johnson, 1975; Dell and McComb, 1978; Ehleringer, 1984
Increased light reflectance (including UV)	ST and GST	Ehleringer, 1984
Decreased water loss through reflection	ST and GST	Ehlringer, 1984
Reduced mechanical abrasion	ST and GST	Uphof, 1962; Johnson, 1975
Protection of phylloplane organisms	ST and GST	Beattie and Lindow, 1999
Reduced leaf wetness	ST and GST	Brewer and Smith, 1997
Reduced photosynthesis thru reflectance	ST and GST	Ehleringer, 1984
Seed dispersal and establishment	ST and GST	Uphof, 1962; Werker, 2000
Epidermal Ca++ homeostasis	ST and GST	DeSilva et al., 2001
Pollen collection and dispersal	ST and GST	Uphof, 1962; Werker, 2000
Provide insect and herbivore deterrence	GST	Johnson, 1975; Kelsey et al., 1984;Wollenweber, 1984;Bennett and Wallsgrove, 1994; Berenbaum, 1995
Insect immobilization	GST	Kennedy, 2003
Fungal and bacterial toxicity/nutrition	GST	Johnson, 1975; Behnke, 1984
Pollinator attraction	GST	Werker, 2000
Ion and pollutant metal secretion	GST	Salt et al., 1995 Choi et al., 2001; Kupper et al., 2000
Water retention and decreased desiccation in seeds	GST	Werker, 2000
Allelopathy	GST	Macias et al., 1999; Werker, 2000
Assist in climbing, and seed establishment	ST	Uphof, 1962; Werker, 2000
Absorb water and nutrients	ST	Uphof, 1962; Sakai et al., 1980; Werker, 2000
Guide pollinators	ST	Johnson, 1975
Water and ion secretion	HT	Johnson, 1975; Aloni et al., 2003

* ST, simple trichomes; GST, glandular secreting trichomes; HT, hydathode trichomes.