Seedless Vascular Plants (Pteridophytes)
Work in progress…
Seedless vascular plants represent an early and important stage in the evolution of land plants. Unlike bryophytes, they possess true vascular tissue (xylem and phloem), allowing them to transport water and nutrients internally and grow taller than their non‑vascular relatives. However, like mosses and liverworts, they still reproduce via spores rather than seeds.
This group includes ferns, horsetails, and clubmosses — lineages that dominated ancient landscapes long before flowering plants evolved. Today they persist in a wide range of habitats, from damp woodland floors to arctic tundra, often thriving in places where seed plants struggle. Their intricate fronds, jointed stems, and scale‑like leaves make them some of the most distinctive plants in the field.
All seedless vascular plants belong to Phylum Tracheophyta (Vascular Plants). Within this phylum, iNaturalist recognises two classes that include all ferns, horsetails, clubmosses, spikemosses, and quillworts. These are:
- Class Lycopodiopsida — Lycophytes (Clubmosses, Spikemosses & Quillworts)
- Class Polypodiopsida — Ferns (& Horsetails)
Class Lycopodiopsida — Clubmosses & Allies
These ancient vascular plants represent some of the earliest diverging lineages within Tracheophyta. Although small today, their ancestors once formed vast forests. Modern species typically grow in nutrient‑poor or seasonally wet habitats, with simple leaves and distinctive strobili (cone‑like reproductive structures).
Orders
- Order Lycopodiales — Clubmosses
- Order Selaginellales — Spikemosses
- Order Isoetales — Quillworts
Observations: none yet
Class Polypodiopsida — Ferns (& Horsetails)
Polypodiopsida is a diverse group that includes all true ferns, horsetails, and several ancient fern lineages. Although united by their spore‑based reproduction, these plants vary widely in form — from delicate filmy ferns to robust horsetails and large tropical marattioid ferns. Their complex fronds, jointed stems, and varied life histories make them one of the most recognisable groups of vascular plants.
Subclass Equisetidae — Horsetails
Horsetails are instantly recognisable by their jointed, hollow stems and whorled branches. They thrive in damp soils, river margins, and arctic tundra, often forming dense colonies. Their reproductive structures are borne in cone‑like strobili at the tips of stems.
- Order Equisetales — Horsetails
- Family Equisetaceae
My Observations
- Equisetum arvense ssp. alpestre — Polar Horsetail (Svalbard)
- Equisetum scirpoides — Dwarf Horsetail (Svalbard)
- Equisetum variegatum — Variegated Horsetail (Svalbard)
- Equisetum sp. — Horsetail / Mare’s‑tail (UK)
Gallery
Subclass Polypodiidae — Leptosporangiate Ferns
The largest and most familiar fern group, including tree ferns, royal ferns, filmy ferns, and most temperate woodland species. Their fronds unfurl from fiddleheads, and their spores are produced in characteristic clusters (sori) on the underside of leaves.
Orders
- Order Cyatheales — Tree ferns
- Order Gleicheniales
- Order Hymenophyllales — Filmy ferns and Bristle Ferns
- Order Osmundales — Royal Ferns
- Order Polypodiales — Many common ferns
- Order Salviniales — Floating and aquatic ferns
- Order Schizaeales
My Observations
- Order Osmundales » Family Osmundaceae »
- Osmunda regalis — Royal Fern (UK)
- Order Polypodiales » Family Cystopteridaceae »
- Cystopteris dickiana — Dickie’s Bladder Fern (Svalbard)
Gallery
Subclass Ophioglossidae — Adder’s‑tongues, Fork Ferns, and Allies
This group includes unusual ferns with simple fronds and distinctive fertile spikes. They often grow in grasslands, woodland edges, and nutrient‑poor soils.
- Order Ophioglossales — Adder’s-tongues and Allies
- Order Psilotales — Fork and Chain Ferns
Subclass Marattiidae — Potato Ferns and Allies
A small, mostly tropical group of large, fleshy‑stemmed ferns.
- Order Marattiales