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Psilotum is a genus of fern-like vascular plants.It is one of two genera in the family Psilotaceae commonly known as whisk ferns, the other being Tmesipteris.Plants in these two genera were once thought to be descended from the earliest surviving vascular plants, but more recent phylogenies place them as basal ferns, as a sister group to Ophioglossales.
The sporangia were from Psilophyton, but some aerial stems were from what is now Sawdonia, and the rhizomes were from Taeniocrada. [17] In 1871, Dawson described specimens which had strong spines as P. princeps var. ornatum. He considered that groups of paired terminal sporangia found with these were part of the same plant, although no actual ...
The family contains two genera, Psilotum and Tmesipteris. The first genus, Psilotum , consists of small shrubby plants of the dry tropics commonly known as "whisk ferns". The other genus, Tmesipteris , is an epiphyte found in Australia , New Zealand , and New Caledonia .
Brace roots may remain aerial or penetrate the soil as they perform root functions such as anchorage and resource acquisition. Although brace root development in soil or aerial environments influences function, a lot is still unknown about how their anatomy, architecture and development contributes to their function. The physiology of brace ...
Psilotum has been interpreted as producing sporangia (fused in a synangium) on the terminus of a stem. Equisetum always produce strobili, but the structures bearing sporangia (sporangiophores) have been interpreted as modified stems. The sporangia, despite being recurved are interpreted as terminal.
The stem is either underground or aerial. The leaves may be microphylls or megaphylls . Their other common characteristics include vascular plant apomorphies (e.g., vascular tissue ) and land plant plesiomorphies (e.g., spore dispersal and the absence of seeds ).
In plant anatomy and evolution a microphyll (or lycophyll) is a type of plant leaf with one single, unbranched leaf vein. [1] Plants with microphyll leaves occur early in the fossil record, and few such plants exist today. In the classical concept of a microphyll, the leaf vein emerges from the protostele without leaving a leaf gap. Leaf gaps ...
Grapevine tendrils and leaves. Thorns. Cladodes. Aerial stem modifications are modifications to the aerial stems, [1] vegetative buds and floral buds of plants growing in different conditions and which perform functions such as climbing, protection, support, synthesis of food, or vegetative propagation.