A strobilus (plural strobili) is an organ of many
plants that contains the reproductive structures. Strobili are ordinarily called cones in many of these groups. Strobili are characterized by a central axis (anatomically a stem) surrounded by spirally arranged or decussatestructures that bear sporangia or other reproductive parts.
The nature of the lateral organs varies among different plant lineages, being derived from either
leafor stem. Leaves that bear sporangia are often called "sporophylls", whereas stems are called "sporangiophores".
Some members of two of the three modern classes of
Lycopodiophyta(the Lycopodiopsidaand the Selaginellopsidaproduce strobili. In all cases, the lateral organs of the strobilus are microphylls bearing meiosporangia. In other members of both classes, ordinary foliage leaves (trophophylls) can act as sporophylls, and there are no organized strobili.
The single extant genus of the
Equisetophyta, " Equisetum", produces strobili in which the lateral organs are called sporangiophores. Developmental evidence and comparison with fossil members of the phylum show that the sporangiophores are reduced stems, rather than leaves.
With the exception of flowering plants, seed plants produce
ovules and pollenin different structures. Strobili bearing microsporangia are called "microsporangiate strobili" or "pollen cones", and those bearing ovules are "megasporangiate strobili" or "seed cones".
Plants of the
Cycadophytaare ordinarily dioecious; seed cones and pollen cones are produced on separate plants. The lateral organs of seed cones are megasporophylls, modified leaves that bear two to several marginal ovules. Pollen cones possess microsporophylls, each of which may have dozens or hundreds of abaxial microsporangia.
The single living member of the
Ginkgophyta, "Ginkgo biloba" produces pollen cones, but the ovules are borne in pairs at the end of a stem, not in a strobilus.
Pollen cones of the
Pinophytaare similar to those of cycads (although much smaller) and Ginkgoes, in that they have microsporophylls with microsporangia on the abaxial surface. Seed cones of many conifers are "compound strobili"; the central stem produces bracts (free in Pinaceae, and espedially notable in Douglas-fir), but fused to the cone scales at maturity in many conifers; in the axil of each bract is a "cone scale", which itself is a reduced strobilus. Ovules are produced on the adaxial surfaces of the cone scales. There are no megasporophylls.
Gnetophytaconsists of three genera, "Ephedra", " Gnetum", and " Welwitschia". All three are ordinarily dioecious, although some "Ephedra" species exhibit monoecy. In contrast to the conifers, which often have compound seed cones, gnetophytes have compound pollen cones. The seed cones of "Ephedra" and "Gnetum" are very reduced, with two and one ovules, respectively, per cone.
flowerof flowering plantsis sometimes referred to as a bisexualstrobilus. Stamens include microsporangiawithin the anther, and ovules (contained in carpels) are megasporangia. Magnoliahas a particularly strobiloid flower with all parts arranged in a spiral, rather than as clear whorls.
A number of flowering plants have
inflorescences, usually catkins, that resemble strobili, but are more complex in structure than strobili.
Evolution of strobili
It is likely that strobili evolved independently in most if not all these groups. This evolutionary convergence is not unusual, since the form of a strobilus is one of the most compact that can be achieved in arranging lateral organs around a cylindric axis, and the consolidation of reproductive parts in a strobilus may optimize spore dispersal and nutrient partitioning.
Gifford, E. M. & Foster, A. S. (1988). "Comparative morphology of vascular plants", 3rd ed. New York: WH Freeman.
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Strobĭlus — Strobĭlus, Zapfen, s. Blüthenstand D) b) bb) … Pierer's Universal-Lexikon
Strobĭlus — (lat.), der Zapfen der Koniferen … Meyers Großes Konversations-Lexikon
Strobilus — [lateinisch »Zirbelnuss«], Botanik: Zapfen … Universal-Lexikon
STROBILUS — Graece ςτρόβυλος seu ςτροβύλιον, proprie pineam nucem siguificat, qualem in insignibus suis Augustam Vindelicorum praeferre, ex Velsero diximus, suô locô: ob similitudinem, Inauris genus, gestamen ex auro Barbarorum quorundam. Ideo Beatus… … Hofmann J. Lexicon universale
strobilus — [strō bī′ləs] n. pl. strobili [strō bī′lī΄] [ModL < LL: see STROBILE] 1. CONE (n. 3) 2. STROBILA (sense 1) … English World dictionary
strobilus — , plural strobili. Reproductive structure of gymnosperms and some cryptogams such as Selaginella; organized collection of sporophylls on a central axis. See also cone, megasporangiate strobilus, microsporangiate strobilus … Expanded glossary of Cycad terms
strobilus — /stroh buy leuhs/, n., pl. strobili / luy/. Bot. 1. a reproductive structure characterized by overlapping scalelike parts, as a pine cone or the fruit of the hop. 2. a conelike structure composed of sporophylls, as of the club mosses and… … Universalium
Strobilus — Stro|bi|lus der; , ...li <aus nlat. strobilus »Fruchtzapfen«, dies aus gr. stróbilos »Kreisel«> Zapfen (bei Nadelhölzern; Bot.) … Das große Fremdwörterbuch
strobilus — stro•bi•lus [[t]stroʊˈbaɪ ləs[/t]] also stro•bile [[t]ˈstroʊ baɪl, bɪl[/t]] n. pl. bi•li( bī′lī) also biles. 1) bot (boi pln) a reproductive structure characterized by overlapping scalelike parts, as a pine cone or the fruit of the hop 2) bot… … From formal English to slang
strobilus — noun (plural strobili) Etymology: New Latin, from Late Latin, pinecone, from Greek strobilos twisted object, top, pinecone, from strobos action of whirling; akin to Greek strephein to twist Date: 1771 1. an aggregation of sporophylls resembling a … New Collegiate Dictionary