How do Psilotales reproduce?
The sporophyte reproduces asexually by the formation of spores. Spores are produce in special tri-lobed structure called synangia. At maturity, many of the dichotomously branched aerial shoots become fertile and produce tri-locular sporangia known as synangia.
What is distinctive about the leaves of the Ophioglossales Ophioglossaceae the Ophioglossoid ferns?
The ophioglossoid ferns are unique in that each leaf (or “frond”) consists of a sterile segment, which contains the photosynthetic blade or lamina, and a fertile segment, bearing the sporangia.
Are Psilotales sporophyte dominant?
PSILOTALES — WHISK FERNS. Like all vascular plants, the whisk ferns have an independent, dominant, free-living sporophyte; the haploid gametophyte is small, obscure, and free-living in or on the soil.
Do Psilotales have roots?
Whisk ferns in the genus Psilotum lack true roots but are anchored by creeping rhizomes. The stems have many branches with paired enations, which look like small leaves but have no vascular tissue. The gametophyte of Psilotum is unusual in that it branches dichotomously, lives underground and possesses vascular tissue.
Is Psilotum a Lycophyte?
The simplest are scalelike emergences, or enations, that are not served by vascular tissue (i.e., they have no veins), found in some extinct groups and in modern whisk ferns (Psilotum). The lycophytes have scalelike, needlelike, or awl-shaped “microphylls” with a single, unbranched vein.
How many diploid number of chromosomes are present in Ophioglossum?
Ophioglossum reticulatum has the highest recorded chromosome count of any organism (cited in different studies as 2n = 1260 or, recently, as n = 760, the latter equivalent to 2n = 1520!).
Where is Psilotum usually found?
Psilotum nudum, one of two species in the genus Psilotum, is widely distributed across tropical and sub-tropical areas of the Americas, Africa, Asia and Australasia, with a small, endangered population found in southern Spain.
Why is it called whisk fern?
Its common name, whisk fern, alludes to its use in the past as a small broom, made by tying a handful of its branches together. It is sometimes found in cultivation (either accidentally, as a weed in greenhouses, or deliberately, in the form of a number of cultivars).