Peltate Sentence Examples
The leaves of the cypresses are scale-like, overlapping and generally in four rows; the female catkins are roundish, and fewer than the male; the cones consist of from six to ten peltate woody scales, which end in a curved point, and open when the seeds are ripe; the seeds are numerous and winged.
Cotyledon, a widely distributed genus with about 90 species, is represented in the British Isles by C. Umbilicus, pennywort, or navelwort, which takes its name from the succulent peltate leaves.
The petiole is inserted a little above the base, and hence the leaf is called peltate or shieldlike.
The formation of peltate leaves has been traced to the union of the lobes of a cleft leaf.
The order is divided into five tribes by characters based on differences in position of the ovules - which are generally semianatropous so that the seed is peltate with the hilum in the centre on one side (or ventral), but sometimes, as in Hottonia and (From Strasburger's Lehrbuch der Botanik.) FIG.Advertisement
It climbs by means of the long stalk of the peltate leaf which is sensitive to contact like a tendril.
Each carpel terminates in a peltate head.
These are often wedge-shaped and angular; in some cases they consist of a short, thick stalk, terminating in a peltate expansion, or prolonged upwards in the form of a triangular lamina.
In Cycas revoluta and C. circinalis each leaf-like carpel may produce several laterally attached ovules, but in C. Normanbyana the carpel is shorter and the ovules are reduced to two; this latter type brings us nearer to the carpels of Dioon, in which the flower has the form of a cone, and the distal end of the carpels is longer and more leaf-like than in the other genera of the Zamieae, which are characterized by shorter carpels with thick peltate heads bearing two ovules on the morphologically lower surface.
This similarity is closest in Archaeocalamites, an ancient type found in Upper Devonian rocks; in this the strobilus consists of peltate sporangiophores inserted in whorls on the axis.Advertisement
In Sphenophyllum fertile both the ventral lobes of the sporophyll (corresponding to the sporangiophores in other species) and the dorsal lobes, which in other species are sterile, were developed as peltate sporangiophores.
In Cycas the altered leaf, upon the margin of which the ovule is produced, and the peltate scales, from which they are pendulous in Zamia, are regarded by all botanists as carpellary leaves.
Diagrammatic longitudinal section of cone, showing the axis (ax) bearing the bracts (br) with peltate sporangiophores (sp) springing from their axils; sm, sporangia.
Diagrammatic longitudinal section of the cone, showing the axis (ax) bearing alternate whorls of bracts (br) and peltate sporangiophores (sp) with their sporangia (sm).
Dawsoni in the fact that each sporangiophore bears two sporangia, attached to a distal expansion approaching the peltate scale of the Equisetales.Advertisement
The recently discovered species, Sphenophyllum fertile, while resembling Bowmanites Romeri in its peltate, bisporangiate sporangiophores, is peculiar in the fact that both dorsal and ventral lobes of the sporophyll were fertile, dividing in a palmate manner into several branches, each of which constitutes a sporangiophore.
The dorsal segments are sterile, corresponding to the bracts of Sphenophyllum Dawsoni, while the ventral segments constitute peltate sporangiophores, each bearing four sporangia, just as in a ax FIG.
Some shoots are sterile while others are fertile, bearing at the apex the so-called fructification - a dense oval, oblong conical or cylindrical spike, consisting of a number of shortly-stalked peltate scales, each of which has attached to its under surface a circle of spore-cases (sporangia) which open by a longitudinal slit on their inner side.
R. tabularis is a bold-growing and handsome species with huge peltate leaves and plumes of cream-white flowers.
From each segment, near its base, a stalked peltate sporangiophore arose; this bore four sporangia, which hung parallel to the stalk.Advertisement
Part of cone, showing the axis (ax) bearing peltate sporangiophores (sp) without bracts; sm, sporangia.