A bulbous trichome is a minute glandular trichome made of a few cells: a one- or two-celled base and a small secretory head, often only 10-30 µm across. They occur widely on leaves, stems and bracts of cannabis plants of both sexes. Their contribution to total resin is small because each holds so little.
In practice
Most growers never notice bulbous trichomes; even with a 60x loupe they appear as faint specks among larger glands. They are mainly of interest in botanical descriptions, in microscopy of trichome development, and when explaining why some resin is found even on leaves that carry few visible glands.
When people grade frost or count glands for harvest, they are looking at capitate-stalked heads, not bulbous ones.
The three-way classification (bulbous, capitate-sessile, capitate-stalked) comes from classic microscopy of cannabis epidermis and is still used in current research.
Don't confuse with
- Capitate-sessile trichome: larger head, sits on the surface without a tall stalk.
- Capitate-stalked trichome: the big mushroom gland on bracts.
- Cystolith trichome: non-glandular hair with a calcium carbonate crystal.
