Nepedia
Back to Discover
Advanced Reader
🧬

Selaginella

life science Maturity 11-13 Next article →

Selaginella is a diverse genus of lycophytes commonly known as spikemosses or lesser clubmosses. This group contains over 750 known species that play important roles in various ecosystems. While they are often called "fern allies," they are actually a distinct group of vascular plants. They are found mostly in tropical regions across the world. However, a few species inhabit the cold arctic-alpine zones of both hemispheres. These plants are incredibly ancient, with fossils dating back over 300 million years to the Late Carboniferous period.

Selaginella selaginoides - Niitvälja bog
Selaginella selaginoides - Niitvälja bog

The physical structure of Selaginella is quite specialized. These plants feature branching stems that may creep horizontally along the ground or grow in an upright position. Their leaves are small and scale-like, which scientists call microphylls. In most lycopods, these leaves have a single unbranched vein, but some Selaginella species possess a branched vascular trace. Inside the stems, the vascular system consists of polystelic protosteles. This means the stem section shows more than two protosteles. Each stele is made of diarch xylem and exarch xylem, which grows outward. These steles connect to the cortex through tube-like structures called trabeculae. These trabeculae are modified endodermal cells that feature casparian strips on their lateral walls.

Selaginella canaliculata
Selaginella canaliculata

Reproduction in Selaginella relies on a process called heterospory. This means the plants produce two different sizes of spores: megaspores and microspores. In certain species, such as Selaginella rupestris, fertilization occurs while the megaspore is still attached to the parent plant. The spore is only released once the embryo has already produced its root and cotyledons. This method ensures the young plant has a head start in its environment. This complex reproductive cycle is a key feature that distinguishes them from many other plant groups.

Spikemoss Selaginella Tamariscina curled up
Spikemoss Selaginella Tamariscina curled up

One of the most remarkable traits in this genus is poikilohydry. This is the ability to survive extreme dehydration. Under very dry conditions, some species can roll up into tight, brown or reddish balls. In this dormant state, they can even be uprooted from the soil. When moisture returns, they rehydrate, turn green, and resume growth. Plants like Selaginella bryopteris are famously called resurrection plants because of this ability. This survival mechanism is linked to tandem gene duplications, which help the plants tolerate desiccation. This is different from the whole genome duplication seen in other evolutionary histories.

Iridescent fern
Iridescent fern

Selaginella species have also evolved unique ways to manage light through their chloroplasts. Chloroplasts are the parts of a cell that handle photosynthesis. About 70% of Selaginella species are monoplastidic, meaning they have one single, giant chloroplast per cell. This is a specialized adaptation for living in very low-light conditions. These monoplastidic species receive only 0.4% to 2.1% of full sunlight. In contrast, species with multiple chloroplasts per cell live in open areas. These species receive an average of more than 40.5% of full sunlight. This shows how the genus has adapted to many different light levels.

The taxonomy, or scientific naming, of Selaginella has a long and complex history. The name was first established by Palisot de Beauvois for the species Selaginella selaginoides. Over time, many scientists have attempted to divide the genus into different groups. For example, some researchers suggest using names like Bryodesma or Lycopodioides to separate certain species. In 2004, a study by Korall and Kenrick used DNA sequences to show that the Euselaginella group is very ancient. This group includes the type species and a Hawaiian species called Selaginella deflexa. More recently, in 2023, scientists Zhou and Zhang suggested the genus could be broken into 19 different genera.

Selaginella-wallacei
Selaginella-wallacei

Today, Selaginella remains a subject of great scientific interest. The species Selaginella moellendorffii serves as an important model organism for researchers. Its entire genome has been sequenced by the Joint Genome Institute of the United States Department of Energy. This allows scientists to study the fundamental mechanics of plant life. Many species are also popular in cultivation due to their beauty. You might find Selaginella kraussiana, known as golden clubmoss, or the iridescent Selaginella willdenowii in many collections. These plants continue to provide deep insights into how life adapts to a changing world.

682 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (5)
File:Spikemoss Selaginella Tamariscina curled up.jpg
Spikemoss Selaginella Tamariscina curled up.jpg
File:Selaginella-wallacei.JPG
Selaginella-wallacei.JPG
File:Selaginella canaliculata.jpeg
Selaginella canaliculata.jpeg
File:Selaginella selaginoides - Niitvälja bog.jpg
Selaginella selaginoides - Niitvälja bog.jpg
File:Iridescent fern.jpg
Iridescent fern.jpg
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.