Psilotum nudum (Whisk Fern, Moa)

Relatives of ferns and horsetails (all Polypodiophyta), and club mosses (Lycopodiophyta) to a lesser degree, Whisk Ferns are peculiar tropical plants that do not produce leaves, root, cones, or flowers. They are simply, Y-branching vascular seedless plants that can be terrestrial or epiphytic.

Psilotum nudum (Whisk Fern, Moa)
Family: Psilotaceae
Subspecies: roughly 100 cultivars have been produced
Native: tropical regions (including Hawaii)
Hardiness Zones: 8-11
Height: to 50 centimeters
Diameter: aerial shoots to 4 mm in diameter, spreads 30 centimeters in diameter at maturity
Root System: rhizomatous, no roots
Growth Rate: fast (considered weedy)
Age: perennial (persist for longer than 5 years)
Deciduous: no
Monoecious/dioecious: bisexual, homosporous (monoecious)

Tolerates: most pests (rarely bothered by them), dry soil
Problems (major): none
Problems (minor): weedy in greenhouses, rather poor salt tolerance
Poisonous: no
Soil requirements: prefers moist conditions, survives in some dry regions, pH 5.6-7.5 (weakly acidic), requires good drainage
Air requirements: requires high humidity and warmth ( keep above 13 C or 60 F)
Watering requirement: moderate
Sun requirement: full sun to partial shades
Vascular tissue: present
Leaves: absent
Shoot: green stem with stomates (gas exchange), protostele (similar to pith) in cener of vascular tissue surrounded by endodermis
Roots: absent, rhizome present
Dominant generation: sporophyte
Gametophyte: saprophytic (absorbs nutrients from soil), heart or pill shaped, to 2 mm long
Sporophyte: medium green
Strobili: lateral, yellow clusters of synagria (three fused sporangia) interspersed on upper portion of foliage atop enations (leaf-like non-vascular structures supporting the synagria), produce spores
Thallus body: absent
Gemmae cups: absent
Epiphyte: yes (grows in soil, however)
Notable characteristics:
These have vascular tissue but lack leaves, roots, and any seeds. Despite this, they are affected by few pests and do very well for themselves.

Uses:
These are commonly grown at universities for their unique physiological structures and taxonomic placement.
Sources used:

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Mature syrangia and Y-shape at the Plant Biology greenhouse at Southern Illinois University Carbondale
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Foliage and enations holding up developing syrangia
All of the images provided were taken by me. They may be used for educational/informational purposes only, provided that this article/online journal is appropriately cited first.

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