Bring a Fern Baby Home for Mother's Day (Science Rendezvous)

Below is information about preparations for the Science Rendezvous (Bring a Fern Baby Home for Mother's Day) event (Markham: 2012--2014)

Fern Biology

C-fern male and hermaphrodite gametophytes

The objective is to reveal the remarkable dynamics of the life cycle of a fern, using microscopy to view the swimming spermatozoids that fertilize the gametophyte and give rise to a fern parent.


C-fern life cycle Ferns have two generations: the diploid sporophyte (what we usually identify as a fern) and haploid gametophytes. The gametophytes are difficult to find because they are so small, growing on the surface of the soil beneath the parental ferns. Two gametophytes must mate to produce the new diploid parental fern generation.

In the context of science education, the material can be presented at multiple levels. For children, being able to observe swimming cells under the microscope engages their natural curiosity. For older people, it provides an opportunity to introduce them to the complexities of biological life cycles.


Preparing the material for Science Rendezvous requires access to techniques and equipment common to biology teaching labs at the University level. Using sterile technique, fern spores are germinated on agar plates containing a defined mix of salts, and at a well-controlled temperature and lighting. The details are available on the Web, at the C-Fern Project Website. The spores can also be germinated on moist soil in plant pots that are covered with plastic wrap to keep the humidity high. Once germinated, the size of the gametophytes is only about 1-2 mm, so magnifying lenses should be used to view them in greater detail.

dishes containing gametophytes in an incubator Once the spores have germinated, it takes about 10 days for them to reach maturity. The mature gametophytes in dishes are brought to the Science Rendezvous event.

C-fern male and hermaphrodite gametophytes When water is added to the dishes, the spermatozoids are released (this may take a few minutes or so) and swim to the female part of the hermaphrodite gametophytes and fertilize the female egg cell. This can be seen by the participants using a dissecting microscope. Finally, the plates can be wrapped with parafilm (or plastic wrap) to keep the newly-made fern babies moist and taken home.

growing C-ferns Click on the picture on the right for instructions on how to grow your Fern Babies once you take them home!

Fern Development

Once fertilized, it will take 3-4 months for the ferns to reach maturity. To begin with they are very small (about 5 mm). Young C-Fern sporophyte

Over the first few weeks after transplanting them to soil, they develop more and more leaves. Developing sporophyte

C-ferns in pots After 3-4 months, they reach maturity. We grow them in a hot greenhouse (about 28 degrees Celsius) at about 50% full sunlight. They are fertilized weekly. We use glass cylinders to provide a higher humidity for the ferns as they grow. The fern fronds have different shapes. The fertile (spore-bearing) fronds are thin and round (wiry). On their undersides, the developing spores can be seen by unfurling the rolled edges of the leaf. leaf unfurled to show the developing spores

Chara Streaming and Pond Life Forms

The objective is to give the public an opportunity to view aquatic life forms that are common in Ontario ponds.

Chara life form Chara aquaria tanks Small aquarium tanks of Chara (and assorted pond life in the tanks) were provided. The participants could obtain samples from the aquaria to look at under the dissecting microscopes. The large cells of the Chara algae could be harvested with forceps and a small pair of scissors. The dramatic cytoplasmic streaming can be readily viewed under a microscope.

snail cleaning Chara cells Snails are usually grown with Chara......... to keep the aquaria tanks clean!

We routinely grow Chara for teaching labs at the University (in both Biology and Biophysics lab courses). Details on how to grow Chara are provided at the Biology Wiki.

Fern Development Images

The objective is to provide imaging of the developmental stages of fern development from the spore to the young sporophyte.

The plates were inoculated on Monday 25 August 2014 and placed in the Sanyo incubator set to 27.5 degrees Celsius with 80% illumination (a photon flux of about 65 micromoles per square meter per second of photosynthetically active radiation). Please feel free to use the photographs (click on the photos for the large version). The formal Creative Commons license is Attribution 4.0 International.

Day 4

After four days at 28 degrees Celsius, some of the spores are just beginning to germinate. First to emerge are rhizoids, which anchor the spores in the substrate.Day Four spores and germination

Day 7

After seven days at 28 degrees Celsius, most of the spores have germinated. The photosynthesizing 'leaf' is just emerging from some of the spores.Day Seven spores and emergence of the leaf

Day 9

After nine days at 28 degrees Celsius, the gametophytes continue to develop. At this stage, it is possible to distinguish between male gametophytes (with a tongue or strap-shaped photosynthetic thallus) and hermaphrodite gametophytes (with a broad photosynthetic thallus). Day Nine gametophyte development: both male and hermaphrodite Day Nine male and hermaphroditic gametophytes

Day 10

After ten days at 28 degrees Celsius, the sex of the gametophytes becomes clearer. They are not yet mature, but should be in a few days Day Ten male and hermaphrodite gametophyte development

Day 11

After eleven days at 28 degrees Celsius, the gametophytes are nearing maturity. The hermaphrodite gametophytes (now mitten-shaped) are beginning to develop the archegonium near the notch. Day Eleven hermaphrodite notch development

Day 14

After fourteen days at 28 degrees Celsius, the gametophytes have reached maturity, and are fully primed for fertilization. Day Fourteen mature gametophytes

After adding distilled water, the spermatozoids are released and swarm near the archegonium of the hermaphrodite. The images were taken about 20 seconds apart, spermatozoid locations are marked in the lower panels. Day Fourteen spermatozoid swarming

A high magnification movie [1.2 MB .mov format] of the swimming behaviour of the spermatozoids can be viewed by clicking on the photo below. Day Fourteen spermatozoid swimming

Day 17

Just a few days after fertilization, the new fern baby is visible as a bump at the notch of the hermaphrodite. Day Seventeen sporophyte (baby) bump visible

Day 21

After twenty-one days, the new fern babies are developing their first leaf. Note that the hermaphrodites are becoming pale as they provide nutrition to the new fern babies. Day Twenty-One day sporophyte (babies) developing

Day 25

After twenty-five days, the more mature fern babies are developing a root. Day Twenty-Three day sporophyte (babies) developing a root

Day 28

After twenty-eight days, secondary leaves are starting to emerge. On older sporophytes, the developmental stages of the leaves --from initiation to expansion-- are apparent.

Day twenty-eight, secondary leaves start to emerge Up to four emerging leaves at initial to expanding developmental stages
The young sporophytes are ready for transplanting to soil (with gentle care to minimize damage to the new fern babies!)

Day 30

High magnification images at day thirty show details of the leaf initials and emerging leaves.

High magnification images at Day thirty show details of the emerging leaves

Day 49

Now in the greenhouse (in one of the hot zones, 24-28 degrees Celsius), the sporophytes continue to grow.

Ferns growing in the greenhouse, now 49 days old

Day 57

The new baby ferns continue unfurl new leaves from the center of the plant.

Leaves unfurling from the center of the fern, now 57 days old

Day 183

A half year later, the ferns are very mature. The new spores can be found protected in the rolled edges of the underside of the fertile leaves. They are ready to be released to produce more Baby Ferns.

Unrolling the fertile frond leaves reveals mature spores underneath

Here are temperatures and relative humidities [png] in the Incubator (and inside the Plexi-Boxes) from Day 4 to Day 7