R2104 2.3 Describe propagation of ferns by spores

Question 1

Fern terminology

Answer 1

Frond - leaf of fern
Sorus (plu. Sori) -protect the sporangia, found on back for fronds
Sporangia - structures where spores are produced. When Sori are ripe the sporangia swell and split to release the spores
Spores - formed vegetative from parent plant
Indusium - thin flap of tissue which cover sporangia
Sporophyte - this is the familiar fern that is seen. Main vegetative stage and produces spores
Gametophyte - the generation that produces gametes of sex cells
**Prothallus **- gametophyte stage of the fern

Question 2

Easy to propagate fern example

Answer 2

Dryopteris affinis

Question 3

Collection of spores

Fern propagation

Answer 3

1. Should be collected when ripe - sporangia will change from green to shades of yellow, brown or black
2. Most temperate ferns ripen from mid to late summer
3. Select frond or part of frond with ripe sporangia
4. Remove sorus and spores on paper
5. Sieve through 1mm sieve - sorus will remain in sieve and sporangia will fall through
6. Place in a clean envelope (dont use plastic bags as it will encourage mould)
7. Label packet
8. Keep in warm dry atmosphere for 2-3 days
9. A fine dust should collect at bottom of packet

Question 4

Initial sowing of Fern spores

Fern propagation

Answer 4

1. Sterilise the container, for example 8 cm plastic pot. This is vital. Boiling water can be used
2. Fill with appropriate compost - 2 parts sphagnum moss peat and 1 part coarse sand
3. Sterilise compost with boiling water. Cover straightaway with kitchen film and allow to cool completely
4. Sow spores thinly onto surface of the moist compost
5. Maintain high humidity by using plastic bags or cling film
6. Place in propagtor with lid
7. Most species need good but not direct light and a warm temp 15-20 degrees C

Question 5

Fern spore germination

Fern propagation

Answer 5

1. Spores germinate within 1 week
2. Within 3 weeks a green ‘haze’ will appear
3. The heart shape gametophytes (prothalla) will emerge
4. When prothallia are about 1/2 cm should be lightly misted
5. Next is the wait for the sporophyte - it can take up to a year.
6. Potting on should commence when sporophytes are about 3-4cm high
7. If potting on is not done they will compete and self-thin