Understanding cannabis anatomy: Leaves, flowers and trichomes

Understanding cannabis anatomy is fundamental to any successful grow:

**Leaf anatomy:**

*Fan Leaves:*

- Large, palmate leaves with 5-11 fingers

- Main photosynthetic organs of the plant

- Show nutrient deficiencies and health status

- Male plants often have fewer fingers (5-7)

- Female plants usually have more fingers (7-11)

*Sugar leaves:*

- Small leaves directly on the flowers

- Covered with trichomes - hence "sugar"

- Contain THC and other cannabinoids

- Perfect for extracts and edibles

- Often removed during trimming for better appearance

*Leaf shapes according to genetics:*

- Sativa: Long, thin fingers, light green in colour

- Indica: Broad, short fingers, dark green

- Ruderalis: Few fingers (3-5), small

**Stem and structure:**

*Main stem:*

- Carries the entire plant

- Transports water and nutrients

- Hollow stems = often female

- Thick stems = robust genetics

*Internodes:*

- Distance between leaf nodes

- Short internodes = compact growth

- Long internodes = stretchy growth

- Indica: short internodes

- Sativa: long internodes

*Nodes:*

- Connection points between stem and leaves

- Sexual characteristics become apparent here

- New shoots develop at nodes

- Training points for LST and HST

**Root system:**

*Taproot:*

- Main root, grows downwards

- Searches for water in deep layers

- Particularly important for autoflowers

- Transplanting can damage the taproot

*Fine roots:*

- Hair-thin roots for nutrient uptake

- Largest surface area of the root system

- Sensitive to overwatering

- Mykhorrhiza fungi dock here

*Root hairs:*

- Microscopically small hairs

- Enlarge surface area by a factor of 10

- Absorb water and nutrients

- Die off quickly in dry conditions

**Recognise sexual characteristics:**

*Female characteristics:*

- White hairs (pistils) on nodes

- V-shaped calyx (sepals)

- Hollow stems more common

- More compact, bushier growth

*Male characteristics:*

- Small green balls at nodes

- No white hairs

- Thicker, more solid stems

- Faster, higher growth

*Hermaphrodites:*

- Both sexual characteristics

- Mostly caused by stress

- Can pollinate female plants

- Remove or isolate immediately

**Flower anatomy

*Calyx:*

- Sepals, enveloping the seed head

- Trichomes develop here

- Swelling at maturity

- Shape varies according to genetics

*Pistils:*

- White hairs from the calyx

- Catch pollen

- Turn brown in colour when ripe

- Indicator for harvest time

*Bracts:*

- Small leaves around flowers

- Trichome-rich, valuable part

- Protect developing seeds

- Often confused with Sugar Leaves

**Trichome types:**

*Bulbous trichomes:*

- Smallest trichomes (10-30 microns)

- Distributed over the whole plant

- Little cannabinoid production

- Protection against UV and pests

*Capitate-sessile trichomes:*

- Medium sized (25-100 microns)

- On leaves and stems

- Moderate cannabinoid production

- Mushroom-like structure

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