MegasporangiumA spore case that makes megaspores. It holds only four.
MicrosporangiumA spore case that makes microspores. It holds a great many.
MegasporesThe large spores, four to a case.
MicrosporesThe small spores. Each case holds very many.
MegasporophyllA cone leaf that carries a megasporangium.
MicrosporophyllA cone leaf that carries a microsporangium.
LiguleA small flap at the base of every leaf. Lycopodium has none.
Cone axisThe stem of the cone. The sporophylls grow from it.
Lycopodium cone 3
SporophyllA leaf that carries a spore case. Here they are all alike.
SporangiumA kidney-shaped spore case, one on each sporophyll.
SporesSmall spores, all of one size.
The plant 5
Strobilus (cone)A cone of close-set sporophylls at a branch tip.
Leaves (microphylls)Small scale-like leaves in rows along the stem.
StemA creeping stem that forks again and again.
RootsThin roots that branch in the soil. They grow from the tip of a rhizophore.
RhizophoreA leafless branch that grows down to the soil. Roots form at its tip.
How this list was compiled: Every name checked on 2026-10-03 and kept only where two of these use it. (1) C. S. Gager, Fundamentals of Botany, 1916, the chapter on club mosses (public domain), https://archive.org/details/fundamentalsofbo00gagerich : in Lycopodium the cone formed by the crowding of the sporophylls at the apex of the leafy axis, the sporangia on the upper surface of the sporophylls near their insertion on the main axis, the foliage leaves small (microphyllous); in Selaginella a much-branched stem with scale-like leaves, sporophylls forming a cone at the branch tips, the ligule, a sporangium in the axil of each sporophyll, megasporangia with four large megaspores on megasporophylls, microsporangia with numerous small microspores on microsporophylls, the axis of the cone. (2) E. Strasburger and others, A Text-Book of Botany, second English edition, 1903 (public domain), https://archive.org/details/textbookofbotany00stra_1 : Lycopodium clavatum, a creeping stem thickly covered with small leaves, roots from the under side, cones of sporophylls at the ends of erect shoots, each sporophyll with a large reniform sporangium on the upper side at the base, the spores all of one kind; Selaginella, small scale-like leaves in rows, a small ligule at the base of the leaves, terminal cones, each sporophyll with one sporangium, macrosporangia with only four macrospores and microsporangia with numerous spores on the same spike. (3) Wikipedia, text only, Selaginella, Lycopodium, Strobilus, Sporophyll and Heterospory, https://en.wikipedia.org/wiki/Selaginella , https://en.wikipedia.org/wiki/Lycopodium , https://en.wikipedia.org/wiki/Strobilus , https://en.wikipedia.org/wiki/Sporophyll : scale-like leaves (microphylls) on branching stems, which also bear roots; a ligule on each microphyll and sporophyll; megaspores and microspores; megasporophylls and microsporophylls, mixed together or apart, in various patterns; a strobilus has a central axis; in Lycopodium kidney-shaped sporangia with spores of one kind only, on sporophylls in a strobilus at the end of upright stems. For the rhizophore and the roots, added on 2026-10-03, passages read through archive.org full-text search: (4) G. M. Smith, Cryptogamic Botany, volume II, 1938, https://archive.org/details/cryptogamicbotan0002gilb : the roots are borne upon leafless branches (rhizophores); adventitious roots at the apices of leafless downward-growing branches, the rhizophores. (5) H. A. Hyde, A. E. Wade and S. G. Harrison, Welsh Ferns, 1962, https://archive.org/details/welshfernsdescri0000haro : stems producing leafless branches (rhizophores) which bear roots at their tips; leaves small, ligulate. Flora of North America north of Mexico, 1993, Selaginellaceae, https://archive.org/details/introduction0002unse , says the same of the family (rhizophores, modified leafless shoots producing roots; roots branching several times). Licence: own work
The drawing: Drawn for this site on 2026-10-03 from plain geometry; own work, nothing traced. Licence: own work
How it works
A Selaginella strobilus labeled here is cut lengthwise, as a microscope slide shows it. The second drawing is the cone of Lycopodium for comparison, and the third is a whole Selaginella plant.
Read the full guide
Two kinds of spore on one cone
A strobilus is a cone of sporophylls on a central axis. In Selaginella each sporophyll holds one sporangium. A megasporangium makes four large megaspores. A microsporangium makes many small microspores. Each leaf and sporophyll also has a ligule, a small flap at its base.
Lycopodium l.s. strobilus, labeled
The letters l.s. on a slide mean a long section. Cut this way a Lycopodium cone shows sporophylls that are all alike. Each carries one kidney-shaped sporangium, and its spores are all of one size.
The drawing puts megasporangia on the left and microsporangia on the right. On a real cone the two kinds may be mixed.
Older books write macrospore for megaspore. The quiz takes both.
Questions and answers
What is the difference between a Selaginella and a Lycopodium strobilus?
Selaginella makes two kinds of spore on one cone, large megaspores and small microspores, and each of its leaves has a ligule. Lycopodium makes spores of one size only and has no ligule.
How many megaspores are in a megasporangium of Selaginella?
Four. Each megasporangium holds four large megaspores. A microsporangium holds a great many small microspores.
What is the ligule in Selaginella?
A small, thin flap at the base of each leaf and each sporophyll, on its upper side. It is one of the marks that tell Selaginella from Lycopodium.
What is a sporophyll?
A leaf that carries a sporangium. In a club moss the sporophylls are crowded around an axis to form the cone. One that carries a megasporangium is a megasporophyll, and one that carries a microsporangium is a microsporophyll.