Plant parts
Apical meristem
the stem tip that keeps dividing and making new growth
Calyx
the outer leaves that wrap the flower
Cotyledons
the first pair of seed leaves at germination
Fan leaves
the large solar panels; the familiar cannabis leaf shape
Node and petiole
the leaf join on the stem, and the stalk that holds the blade
Pistil
the ovule-bearing part of the flower
Trichomes
glands on leaves and buds that hold THC
Flowering and sex
Short-day plant
flowers after a critical dark period
Auto-flower / ruderalis
flowers without a light-cycle cue
Phytochrome
the red / far-red pigment that gates photoperiod flowering
Sinsemilla
seedless female flowers
Hermaphrodite
male and female flowers on one plant, from genetics, stress, or chemicals
Stretching
internodes lengthen from heat plus weak light
Training and hormones
Supercropping
bend tops horizontal so the main flower gets more light
Crimping
bruise a branch so it bends easier and later thickens
Auxins
hormones that steer shape, roots, and buds
Cytokinins
work with auxin on cell division and side growth
Gibberellins
stretch leaves and shoots across the whole plant
Light, water, and feed
PAR
light from 400 to 700 nanometers that drives photosynthesis
Photosynthesis
light-powered sugar making from water and CO2, releasing oxygen
Transpiration
water vapor leaving mainly through stomata
Fertigation
fertilizer delivered with the irrigation water
Macros
nitrogen, phosphorus, and potassium used in large amounts
Micros
calcium, sulfur, magnesium, iron, copper, manganese, zinc, and boron in the book’s list
Chlorosis and necrotic
loss of green from missing chlorophyll, versus dead leaf patches
Methods and chemistry
Aeroponics
roots hang in a chamber and take a fine, oxygen-rich mist
Rhizosphere
the living community in the soil right around the roots
Friable
mix that holds a clod when squeezed, then crumbles when poked
Ballast
the gear that converts power for a lamp
THC
the main intoxicating cannabinoid; CBD is non-intoxicating and does not bind CB1 the same way
Terpenes
aromatic oils used to attract, repel, or signal; cannabis is wind-pollinated so scent is not for bees