Monilophytes: Horsetails (Equisetopsida) Flashcards
(24 cards)
Monilophytes
Clade of ferns + horsetails discovered using molecular sequence datasets
Four clases of Monilophytes
- Psilotopsida
- Marattiopsida
- Polypodiopsida
- Equisetopsida
Psilotopsida
whisk fern, moonworts
Marattiopsida
marattioid ferns
Polypodiopsida
remaining ferns
Equisetopsida
horsetails and extint relatives
Equisetopsida - Explain
Unusual among monilophites:
- jointed stems
- small leaves in whorls
- whorled branches
- cones
Sporophyte
- Rhizomatous
- leaves and branches are in whorls
- surface of stems has ribs
- ribs alternate from node to node
- Stomata between ribs
Whorl
three or more leaves attached at the same level (node) on stem
Node
region of the stem where a leaf or leaves are attached
Internode
region between two nodes
Silica in epidermis
stem has rough texture (“scouring rush”)
Silica
may be involved in support of stem
peltate
(shield-like) structures that bear sporangia
Strobilus
born at the tips of stems.
comprised of sporangiophores and pelate
sporangium / sporangia
produces spores that germinate into tiny gametophytes.
Sporangiophores
Strobili of whorled peltate structures (sporangiophores) bearing
sporangia on underside
Ribs on sporophyte stem
- Alternate from node to node
2. stomata between ribs
Equisetum
- Homosporous.
2. Only living memeber of Equisetopsida
Elaters on spores
Four elaters on spore wall (help in dispersal).
Sensative to moisture and uncoil as they drie.
Gametophytes on Horsetails
- unisexuial (male) or bisexual
2. Rhizoid-bearing and a “leafy” reagions
homosporous
producing spores of one kind only
Equisetum stem anatomy
- Open canals are associated with the vascular bundles and also occur in the cortex
- There is also a large, hollow pith cavity.
- nodes are solid.
Pith cavity
canal in the center of the stem
