Word Finder - genera

definition

A rank in the classification of organisms, below family and above species; a taxon at that rank.

example

All magnolias belong to the genus Magnolia.

definition

A group with common attributes.

definition

A natural number representing any of several related measures of the complexity of a given manifold or graph.

definition

Within a definition, a broader category of the defined concept.

The pasto duro is largely composed of the genera Stipa and Melica.

The same deposits have also yielded remains of extinct types of kangaroo, some of gigantic size, constituting the genera Sthenurus, Procoptodon and Palorchestes.

Filhol, the fossils themselves represent two genera, Peratherium, containing the greater part of the species, about twenty in number, and Amphiperatherium, with three species only.

Of doubtful position, but commonly referred to the Trachylinae, are the two genera of fresh-water medusae, Limnocodium and Limnocnida.

In some Indian and Malay Engystomatids of the genera Callula and Microhyla, the tadpoles are remarkably transparent, and differ markedly in the structure of the buccal apparatus.

Cells of this type are often called trumpet-hyphae (though they have no connection with the hyphae of Fungi), and in some genera of Laminariaceae those at the periphery of the medulla simulate the sieve-tubes of the higher plants in a striking degree, even (like these latter) developing the peculiar substance callose on or in the perforated cross-walls or sieve-plates.

In a good many cases, sometimes in isolated genera or species, sometimes characteristic of whole families, so-called anomalous cambial layers are formed in the stem, either as an extension of, or in addition to, the original cambial cylinder.

The former is concerned with the division of the earths surface into major districts characterized by particular plants or taxonomic groups of plants, with the subdivision of these floristic districts, and with the geographical distribution (both past and present) of the various taxonomic units, such as species, genera, and families.

Casimir de Candolle has made an independent investigation, based on Hooker and Benthams Genera plantarum.

Though now on the way to extinction, Cycadeae are still widely represented in the southern hemisphere by genera which, however, have no counterpart in the Mesozoic era.

Amongst Conifers the archaic genera, Ginkgo and Araucarus still persist.

In the mountains of Peru we find such characteristic northern genera as Draba, Alchemilla, Saxifraga, Valeriana, Gentiana and Bartsia.

If we turn to herbaceous plants, Hemsley has pointed out that of the thirteen genera of Ranunculaceae in California, eleven are British.

Assuming that in its circumpolar origin the North Temperate flora was fairly homogeneous, it would meet in its centrifugal extension with a wide range of local conditions; these would favor the preservation of numerous species in some genera, their greater or less elimination in others.

On the other hand, it is rich in Cornpositae, especially Solidago and A ster, Polemoniaceae, Asciepiadaceae, Hydrophyllaceae and Cyperaceae, and it has the endemic Sarracenia, type of a family structurally allied to poppies, of which of the remaining genera Darlingtonia is Californian, and Heliamphora Venezuelan.

Its arboreal vegetation is richer both in genera and species than that corresponding to it in the Old World.

Of four genera which Hooker singles out as the largest in Sikkim, in China Corydalis has 76 species, Saxifraga 58, Pedicularis 129, and Primula 77.

Amongst palms Washinglonia, Brahea and Erythea (all Corypheac) replace the eastern genera.

C. de Candolle finds that with one exception the species belong to genera represented in one or other of the Indian peninsulas.

As in the IndoMalayan sub-region, epiphytic orchids are probably most numerous in point of species, but the genera and even sub-tribes are far more restricted in their range than in the Old World; 4 sub-tribes with 74 genera of Vandeae are confined to South America, though varying in range of climate and altitude.

Nearly related to myrtles are Melastomaceae which, poorly represented in the Old World, have attained here so prodigious a development in genera and species, that Ball looks upon it as the seat of origin of the family.

Aroids, of which the tribes are not restricted in their distribution, have two large endemic genera, Philodendron and Anthurium.

Instead of large continuous areas, in which local characteristics sometimes blend, it occupies widely dissevered territories in which specialization, intensified by long se1/2aration, hai mostly effaced the possibility of comparing species hnd even genera and compels us to seek for points of contact in groups of a higher order.

While so many conspicuous Australian elements are wanting in New Zealand, one-eighth of its flora belongs to South American genera.

By the same path it kis received a remarkable contribution from the North Temperate region; such familiar genera as Ranunculus, Epilobfum and Veronica form more than 9% of the flowering plants.

Taking, however, the Andean flora as typical, it contains a very marked endemic element; Ball finds that half the genera and four-fifths of the species are limited to it; on the other hand, that half the species of Gamopetalae belong to cosmopolitan genera such as Valeriana, Gentiana, Bartsia and Gnaphalium.

On the other hand, it is the headquarters of Mutisiaceae, represented in South Africa by such genera as Oldenburgia and Gerbera and by Triehocline in Australia.

Prosotis extends to the Argentine; other characteristic genera are Oenothera, Godetia Collomia, Heliotropium and Eritrichium.

On the whole, it consists of local species of some widely distributed northern genera, such as Carex, Poa, Ranunculus, &c., with alpine types of strictly south temperate genera, characteristic of the separate localities.

Forbes had investigated such important genera as Philepitta and Xenicus, P.L.

But it also follows that, if every extinct and recent bird were known, neither species, nor genera, nor families, nor orders could be defined.

Baptornis, another of Marsh's genera, seems to be allied to Enaliornis, Palaeotringa and Talmatornis, were by him referred to Limicoline and Passerine birds.

The upper Eocene has yielded many birds, most of which are at least close forerunners of recent genera, the differentiation into the leading orders and families being already well marked, e.g.

The existing genera include Anas, Aquila, Bubo, Columba, Cypselus, Lanius, Picus, Phalacrocorax, Sula, &c. Very interesting is the fact that Serpentarius, Psittacus and Trogon are amongst this list of birds, which are now restricted to the tropics.

In Colorado and New Mexico Marsh has detected bones of Meleagris, Puffinus, Sula and Uria, all existing genera; but the first is especially suggestive, since it is one of the most characteristic forms of the New World.

New Zealand has also yielded many flightless birds, notably the numerous species and genera of Dinornithidae, some of which survived into the 19th century; Pseudapteryx allied to the Kiwi; Cnemiornis, a big, flightless goose; Aptornis and Notornis, flightless rails; and Harpagornis, a truly gigantic bird of prey with tremendous wings and talons.

The numbers of genera and species of birds are, of course, a matter of personal inclination.

The faunas of the two are as absolutely distinct as those of South America and Africa, and it is only because they are separated by a narrow strait instead of the broad Atlantic that they have become so slightly connected by the interchange of a few species and genera.

All the existing Ratitae (with the exception of the ostriches of Africa and South America, belonging to the genera Struthio and Rhea, and comprising at most but five species) are found in Austrogaea and nowhere else.

Of the Meliphagidae the genera Prosthemadera, Pogonornis and Anthornis are peculiar.

The continent, however, possesses the two important genera of the Pseudoscines, namely the lyre-birds (Menura) and the scrub-birds (Atrichia).

First in point of importance comes the extraordinarily beautiful family of humming-birds (Trochilidae), with nearly 150 genera (of which only three occur in the Nearctic region) and more than 400 species.

To these follow the tanagers (Tanagridae), with upwards of forty genera (only one of which crosses the border), and about 300 species; the piculules (Dendrocolaptidae), with as many genera, and over 200 species; the ant-thrushes, (Formicariidae), with more than thirty genera, and nearly 200 species; together with other groups which, if not so large as those just named, are yet just as well defined, and possibly more significant, namely, the tapaculos (Pteroptochidae), the toucans (Rhamphastidae), the jacamars (Galbulidae), the motmots (Monotidae), the todies (Todidae), the trumpeters (Psophiidae), and the screamers (Palamedeidae); besides such isolated forms as the seriema (Cariama), and the sun-bittern (Eurypyga).

We note the absence of Ratitae, Tinami, Cracidae, Rhamphastidae, and any of those gruiform genera which are so, characteristic of the continent.

The entire number of Palaearctic families are, according to Newton, 67, and of the genera 323.

To compare the Palaearctic genera with those of the Australian and Neotropical regions would be simply a waste of time, for the points of resemblance are extremely few, and such as they are they lead to nothing.

Struthio in Africa and Arabia, fossil also in the Sivalik Hills, and Aepyornithidae in Madagascar; Pittzdae, Bucerotinae and Upupinae, of which Upupa itself in India, Madagascar and Africa; Coraciidae; Pycnonotidae or bulbuls; Trogonidae, of which the Asiatic genera are the less specialized in opposition to the Neotropical forms; Vulturidae; Leptoptilus, Anastomus and Ciconia among the storks; Pteroclidae; Treroninae among pigeons.

Between fifty and sixty so-called families of land birds alone are found within its limits, and of them at least nine are peculiar; the typical genera of which are Buphaga, Euryceros, Philepitta, Musophaga, Irrisor, Leptosoma, Colius, Serpentarius, Struthio, Aepyornis.

Lastly must be noted the extinct tall Ratite species of Aepyornis with its several fancy genera.

We have homely genera, even among the true Passeres, occurring there - such as Alauda, Acrocephalus, Motacilla and Pratincola, while the Cisticola madagascariensis is only distinguishable from the well-known fan-tailed warbler, C. schoenicola of Europe, Africa and India by its rather darker coloration.