Selaginellaceae
Selaginella
Spikemosses — neither mosses nor ferns, but lycophytes, a lineage that split from everything else with veins about 410 million years ago. The holly fern on the next shelf is more closely related to an oak tree than to this. They are heterosporous, producing two sizes of spore where most ferns produce one, and they root from rhizophores along every prostrate stem, which is why a fragment becomes a plant so readily.
Native to Cosmopolitan; the spikemoss grown here is from southern and eastern Africa
How Selaginella generally wants to be treated
Species pages start from this and record only where they differ.
- Light
- Shade to deep shade. It tolerates a remarkable range of light and a remarkable range of temperature; what it does not tolerate is drying out.
- Water
- Permanently damp. This is the whole of it. The substrate should not dry, and the species is not one of the resurrection spikemosses — for this one, dry is dead.
- Humidity
- High. No source publishes a percentage for the genus, and I am not going to borrow the fern figures and relabel them. The documented failure is specific: dry air gives brown, shrivelled foliage.
- Temperature
- Tolerant — a weed in cool-temperate Britain, Ireland, Germany and New Zealand, so the hardiness tag of zones 11-12 that circulates is not a physiological limit. Ordinary room temperature is fine.
- Substrate
- A fine, moisture-retentive mix that will not dry out. Shallow, since it creeps rather than roots down.
- Fertilizer
- No tier 1-3 source gives any feeding guidance for the genus. This record does not invent one.
- Propagation
- Division, or simply pinning a stem down — it roots from rhizophores all along its length.
- Dormancy
- None documented, and the evidence points to there being none.
- Common problems
-
- Brown, shrivelled foliage from dry air — the single documented failure mode
- A substrate allowed to dry, which it does not recover from
- Resenting being lifted or disturbed, since it roots along the whole stem rather than from one crown
- Do not put it on a compost heap or let it escape outdoors in a mild climate: it forms thick forest-floor mats that suppress native seedlings, and nursery potting mix is a named route for spreading it
In the collection
- Frosty fern Selaginella kraussiana (Kunze) A.Braun 'Frosty Fern'