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Fritillaria

Genus of flowering plants

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Species : Fritillaria meleagris Family : Liliaceae Image No. 1
Kurt Stüber [1] · CC BY-SA 3.0

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Through Bulb, Perennial and Species

The name Fritillaria is thought to refer to the checkered pattern of F. meleagris, resembling a box in which dice were carried. Fritillaries are commercially important in horticulture as ornamental garden plants and also in traditional Chinese medicine, which is also endangering some species. Fritillaria flowers have been popular subjects for artists to depict and as emblems of regions and organizations.

Description

General

Fritillaria is a genus of perennial herbaceous bulbiferous geophytes, dying back after flowering to an underground storage bulb from which they regrow in the following year. It is characterised by nodding (pendant) flowers, perianths campanulate (bell- or cup-shaped) with erect segments in upper part, a nectarial pit, groove or pouch at the base of the tepal, anthers usually pseudobasifixed, rarely versatile, fruit sometimes winged, embryo minute.

Specific

Vegetative

Bulbs

The bulbs are typically tunicate, consisting of a few tightly packed fleshy scales with a translucent tunic that disappears with further growth of the bulb. However, some species (F. imperialis, F. persica) have naked bulbs with many scales and loosely attached bulbils, resembling those of the closely related Lilium, although F. persica has only a single scale.

Stems and leaves

The stems have few or many cauline leaves (arising from the stem) that are opposite on the stem or verticillate (arranged in whorls), sometimes with a cirrhose apex (ending in a tendril).

Reproductive

Inflorescence and flowers

The inflorescence bears flowers that are often solitary and nodding, but some form umbels or have racemes with many flowers. The flowers are usually actinomorphic (radially symmetric), but weakly zygomorphic (single plane of symmetry) in F. gibbosa and F. ariana. The campanulate perianth has six tepals, in two free whorls of three (trimerous), that can be white, yellow, green, purple or reddish. The erect segments are usually tesselated with squares of alternating light and dark colours. While the tepals are usually the same size in both whorls, in F. pallidiflora, the outer tepals are wider. The tepals have nectarial pits, grooves (F. sewerzowii) or pouches at their base. In F. persica the nectarial pouch is developed into a short spur. The perigonal nectaries are large and well developed, and in most species (with the exception of subgenus Rhinopetalum), are linear to lanceolate or ovate and weakly impressed upon the tepals. Extrafloral nectaries are present at least the northwest American species according to Mizell 2004.

Gynoecium

The flowers are bisexual, containing both male (androecium) and female (gynoecium) characteristics. The pistil has three carpels (tricarpellary). The ovaries are hypogynous (superior, that is attached above the other floral parts). The ovule is anatropous in orientation and has two integuments (bitegmic), the micropyle (opening) being formed from the inner integument, while the nucellus is small. The embryo sac or megagametophyte is tetrasporic, in which all four megaspores survive. The style is trilobate to trifid (in 3 parts) and the surface of the stigma is wet.

Androecium

Stamens are six, in two trimerous whorls of three, and diplostemonous (outer whorl of stamens opposite outer tepals and the inner whorl opposite inner tepals). Filaments filiform or slightly flattened, but sometimes papillose and rarely hairy (F. karelinii). Anthers are linear to ellipsoid, but rarely subglobose (F. persica) in shape, and their attachment to the filament is usually pseudobasifixed (connective tissue extends in a tube around the filament tip), rarely attached at the centre and free (dorsifixed versatile; F. fusca and some Liliorhiza species). In contrast, pseudobasifixed anthers can not move freely. The pollen grains are spheroidal and reticulate (net like pattern), with individual brochi (lumina within reticulations) of 4–5 μm.

Fruit and seeds

The capsule is obovoid to globose, loculicidal and six-angled, sometimes with wings. The seeds are flattened with a marginal wing, the seed coat made out of both integuments, but the testa is thin and the endosperm lacks starch. The embryo is small.

Phytochemistry

Fritillaria, like other members of the family Liliaceae, contain flavonol glycosides and tri- and diferulic-acid sucrose esters, steroidal alkaloids, saponins and terpenoids that have formed the active ingredients in traditional medicine (see Traditional medicine). Certain species have flowers that emit disagreeable odors that have been referred to as phenolic, putrid, sulfurous, sweaty and skunky. The scent of Fritillaria imperialis has been called "rather nasty", while that of F. agrestis, known commonly as stink bells, is reminiscent of canine feces. On the other hand, F. striata has a sweet fragrance. The "foxy" odor of F. imperialis has been identified as 3-methyl-2-butene-1-thiol (dimethylallyl mercaptan), an alkylthiol.

Genome

Fritillaria represents one of the most extreme cases of genome size expansion in angiosperms. Polyploidy is rare, with nearly all species being diploid and only occasional reports of triploidy. Reported genome size in Fritillaria vary from 1Cx (DNA content of unreplicated haploid chromosome complement) values of 30.15 to 85.38 Gb (Giga base pairs), that is > 190 times that of Arabidopsis thaliana, which has been called the "model plant" and > 860 times that of Genlisea aurea, which represents the smallest land plant genome sequenced to date. Giant genome size is generally defined as >35 pg (34 Gb). The largest genomes in diploid Fritillaria are found in subgenus Japonica, exceeding 85 Gb. At least one species, tetraploid F. assyriaca, has a very large genome. With approximately 127 pg (130 Gb), it was for a long time the largest known genome, exceeding the largest vertebrate animal genome known to date, that of the marbled lungfish (Protopterus aethiopicus), in size. Heterochromatin levels vary by biogeographic region, with very little in Old World and abundant levels in New World species. Most species have a basic chromosome number of x=12, but x=9, 11 and 13 have been reported.

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