To explore the miniature world of cryptogams, start your hunt in bushland. As you explore you might notice delicate fern fronds unfurling, shaggy lichens dripping from branches, or tough, flattened lichens painting bright splashes across rocks.
Visit the same bushland after rains, or explore the ground in damp areas and beside streams, and you might find bryophytes. In moisture-rich environments, these tiny plants flourish, revealing their extraordinary diversity. Soft carpets of moss are the most abundant and easiest to recognise, but hornworts and liverworts can be found here too. Their spores can sit in the ground for years, waiting for rains.
This photo shows two different species of hornworts...
...in two different phases of their life cycles. On the right is Anthoceros palssoniae, a newly named species.
The newly named hornwort Anthoceros palssoniae (right) and a Phaeoceros hornwort (left). Image: Ruth Palsson
This is Fossombronia pseudointestinalis, a new species of liverwort.
Its black capsules are only 1 millimetre in diameter. They are the plant’s reproductive structures, which release microscopic spores into the wind and water. Its lobed leaves are tubular and wavy, like an intestine, hence its name.A cryptic bunch
Cryptogams are a mixed bunch of plants and plant-like lifeforms.
They include mosses, hornworts, liverworts, ferns, fungi, lichens, slime moulds and algae.
Cryptogams are as different as sheep and sharks, but their shared lack of seeds meant their way of reproducing was a mystery to early botanists.
They lumped them together in a group they called cryptogams from the Greek words for ‘hidden’ and ‘reproductive structure’.
In a way, they were right.
Most cryptogams do share a common feature, they reproduce by microscopic spores.
At this scale, the tiny world of cryptogams is even stranger.
Using an electron microscope reveals invisible details. For bryophytes and ferns, the patterns on their spores are often the only way to tell species apart. Some have smooth spores, while others have distinctive patterns or textures.
Digitising our cryptogams
Telling species apart is our speciality. The cryptogam collection of the Australian National Herbarium has 300,000 specimens identified by expert botanists. We’re now bringing them to the world, thanks to digitisation.
On a conveyor belt set up in the middle of the collection, a team from the imaging company Picturae is digitising the entire collection.
At one end of a giant conveyor belt, two people unpack paper packets. Inside each one is a small plastic bag that holds a dried specimen. They lay them on the conveyor belt and pin their labelled packets flat.
A camera takes a high-resolution photograph, capturing the specimen and the information on its label. The conveyor belt moves on, and a third person packs the specimen away.
The cryptogams of the collection are stored in boxes or packets inside metal cabinets and mobile shelving.
Blue packets are for specimens collected overseas; white packets for Australia.
Larger specimens like ferns and seaweeds are pressed and attached to large sheets of paper.
They are kept safe from insect pests, who love to eat dried fungi, but tend to leave bryophytes alone.
Naming new species
Dr Chris Cargill is the head curator at the cryptogam collection.
Drawings of the hornworts Anthoceros apocynon and Anthoceros wellmanii. A to C show whole plants of A. apocynon and D shows one of its spores. E and F show whole plants of A. wellmanii, G shows a cross-section through the sporophyte (adult plant), and H shows different views of its spores. Drawings by Chris Cargill
One of Chris’s passions is hornworts.
“Hornworts are a small group of unusual plants,” she says.
“There are fewer than 250 species worldwide, including only 24 in Australia. But thanks to citizen scientists, Australia has three newly recognised hornworts.”
The new hornworts belong to the genus Anthoceros and can only be told apart by features of their microscopic spores. They were found growing near Narrabri in New South Wales (NSW) at different times, years apart, but all after heavy rains that followed dry periods and drought. Like mosses and liverworts, hornworts require water for their sperm to swim to their eggs.
But wait! Don’t they reproduce by spores? We’re glad you asked.
A cycle of rebirth
Like most cryptogams, seaweeds included, hornworts grow in two distinctive phases – gametophytes and sporophytes.
Hornwort gametophytes tend to look like a flat, circular leaf growing on the soil. They produce eggs and sperm, which swim to eggs either on the same plant or one nearby.
Fertilised eggs begin to grow on the parent gametophyte, forming a sporophyte, a horn-like structure that gives hornworts their name. (Wort simply means plant.)
Sporophytes release microscopic spores into the air. If they find a suitable home, they grow into gametophytes, completing the life cycle.
Our cryptogam collection contains only dried, dead specimens. Or does it?
Even after many years stored in collections, some species of mosses or liverworts can come back to life if they are soaked in water. As glaciers melt, people are discovering mosses still alive after being frozen for hundreds, perhaps thousands, of years.
Unearthing a new genus
Nature still holds millions of surprises if you know where to look.
Dr Cecile Gueidan is studying lichens at the cryptogam collection.
Last year she helped name and describe a new species, Verrucariopsis suaedae, from France, which is also in a new genus (a group of species).
“This was quite a remarkable discovery from my French colleagues, the late Dr Jean-Yves Monnat and Dr Claude Roux, along the coast of Brittany, as it is also a new genus for science. It’s not often we find new genera in the well-known French lichen flora,” Cecile says.
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Among Australian lichens, this year Cecile “undiscovered” several species.
“Lichens can look very different depending on the substrate and environmental conditions in which they grow. This means two named species can sometimes end up being a single species,” Cecile says.
"I am now using DNA techniques to check how different Australian lichen species are related.”
As a result of her molecular work, Cecile collapsed a total of seven apparently different lichen species into just three species. This is called synonymising.
The photos here show two lichens that were synonymised, Trapelia pruinosa and Trapelia rosettiformis. Both species were named in 2020.
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“They look quite similar overall, but initially seemed to differ by the texture of their upper surface, the size of their spores and the presence of calcium oxalate crystals,” Cecile says.
“Our DNA data showed they are more likely to be a single species. Trapelia pruinosa was published first, so the rule is we keep that name.”
Resources in nature
Lichens are symbioses between fungi and algae.
There are more than 20,000 lichenised fungi globally, which pair up with about 300 different algae.
Cecile says in the past lichens were named as new species based on their morphology (how they look) as well as the unique chemicals they produce, which are known as secondary metabolites.
“You can use simple chemicals like bleach and potash to tell some lichens apart. For example, a drop of bleach will turn some lichens pink,” Cecile says.
“We’re using mass spectrometry to create a public spectral library that other researchers can use to identify these compounds. We are also testing the bioactive properties of extracts of some lichens,” Cecile said.
“We are searching for compounds with antimicrobial properties, with the hope of expanding to other bioactive properties.”
The Australian National Herbarium is part of a joint venture between Parks Australia and CSIRO.
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