The key difference between Lycopodium and Selaginella is that Lycopodium is a clubmoss which is homosporous (one type of spore) while Selaginella is a spike moss which is heterosporous (two distinct types of spores).
Lycophyta is a subgroup of vascular plants belonging to Kingdom Plantae. They are also known as fern-allies. They are primitive plants and do not bear seeds, wood, fruits and flowers. Therefore, all lycophytes are herbaceous plants. They produce spores for reproduction. Moreover, lycophytes they have unique leaves called microphylls. There are three families of lycophytes; Lycopodiaceae, Selaginellaceae, and Isoetaceae. Club mosses, quillworts and spike mosses belong to these three families. Lycopodium is a genus of club mosses while Selaginella is a genus of spike mosses.
CONTENTS
1. Overview and Key Difference
2. What is Lycopodium
3. What is Selaginella
4. Similarities Between Lycopodium and Selaginella
5. Side by Side Comparison – Lycopodium vs Selaginella in Tabular Form
6. Summary
What is Lycopodium?
Lycopodium is a genus of club mosses which produce one type of spores. Their spores are alike, numerous and same size. Lycopodium plants are terrestrial herbs or epiphytes. Lycopodium leaves are small and arranged spirally around the stem. Sporophyte is the dominant generation of Lycopodium. Gametophyte is one kind. It is a bisexual gametophyte which is a prothallus.
Figure 01: Lycopodium
Prothallus contains both sperm-producing antheridia and egg-producing archegonia on the same plant. After fertilization, sporophyte develops, and it becomes physiologically independent fro gametophyte.
What is Selaginella?
Selaginella is a genus of spike mosses that includes a total of around 700 species. These plants are delicate herbs. The stem of the Selaginella is creeping and dichotomously branched. Selaginella is a heterosporous plant which produces two different types of spores. Spores are born in sporophylls. Megasporophylls and microsporophylls are present in the same strobilus. Megasporangia are produced in megasporophylls while microsporangia are produced in microsporophylls.
Figure 02: Selaginella
Selaginella leaves are small and have ligules (scale-like outgrowth). Presence of ligules in Selaginella is a distinguishing feature of Lycopodium. Selaginella leaves are arranged in four rows (two rows of short leaves and two rows of long leaves) along the stem. Selaginella grows as epiphytes or on the floor of wet tropical forests.
What are the Similarities Between Lycopodium and Selaginella?
- Both Lycopodium and Selaginella belong to the clade of Lycophyta.
- They are also known as fern-allies.
- They are seedless vascular plants.
- But they are primitive plants that do not seed, wood, fruit and flowers.
- They show alternation of generation.
- Sporophytes are the dominant generation of lycophytes.
- They are herbaceous plants and have adventitious roots.
- They are epiphytic species in both genera.
- Branching is usually dichotomous in both Lycopodium and Selaginella.
What is the Difference Between Lycopodium and Selaginella?
Lycopodium is a genus of club mosses while Selaginella is a genus of spike mosses. Lycopodium plants are homosporous; hence they produce only one type of spores while Selaginella plants are heterosporous; hence they produce two distinct types of spores. So, this is the key difference between Lycopodium and Selaginella.
The below infographic tabulates more differences between Lycopodium and Selaginella.
Summary – Lycopodium vs Selaginella
Lycophytes are seedless vascular plants. They are similar to ferns. They have unique leaves called microphylls. They are primitive plants which lack seeds, woods, fruits and flowers. Lycopodium and Selaginella are two genera of lycophytes. Lycopodium plants are homosporous. Therefore, they produce only one type of spores which are alike, numerous and same size. Selaginella plants are heterosporous. Therefore, they produce two distinct types of spores. Moreover, Selaginella plants have ligules which are scale-like outgrowths. Lycopodium lacks ligules. Thus, this summarizes the difference between Lycopodium and Selaginella.
Reference:
1. “Lycophyte.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., Available here.
2. “Lycopodium.” Wikipedia, Wikimedia Foundation, 23 Oct. 2020, Available here.
Image Courtesy:
1. “Lycopodium clavatum 151207” By Bernd Haynold – Self-photographed (CC BY-SA 3.0) via Commons Wikimedia
2. “Selaginella-sp” By L. Fdez. – Own work (CC BY-SA 2.1 es) via Commons Wikimedia