Spikelet is a type of racemose inflorescence in which two bracts are arranged at the base with one or more florets above e.g., Poaceae … However, many authors have noted the problems with this approach. Harder, L. D., and Prusinkiewicz, P. (2013). doi: 10.1093/aob/mcs252. Species relationships based on Quintanar et al. The WUSCHEL-like genes are less well-studied and no mutants are available, but their basic developmental function is inferred to be similar to those in Arabidopsis. Some species shed naked caryopses such as Sporobolus. Primary branches in Melica are clearly distichous (Figures 6D,E). Mesquite: A Modular System for Evolutionary Analysis, version 2.6. Others shed the entire inflorescence such as Schedonnardus. 51, 1030–1040. NCERT P Bahadur IIT-JEE Previous Year Narendra Awasthi MS Chauhan. Sci. Cambridge, UK: Cambridge University Press. The morphology and developmental genetics of the shift in phyllotaxis have been studied extensively in maize and rice. doi: 10.1080/0028825X.1993.10419494, McKone, M. J., Lund, C. P., and O'Brien, J. M. (1998). Development 132, 1235–1245. Proc. (2000) “A model of inflorescence development,” in Monocots: Systematics and Evolution, eds K. L. Wilson and D. A. Morrison (Melbourne, VIC: CSIRO), 84–88. The inflorescence develops a clear “back” with no branches and “front” with branches (Figures 5C–F). Kurtziana 21, 275–278. Within the grasses, even if the inflorescence meristem produces primordia in multiple orthostichies or parastichies, higher order meristems (primary, secondary, tertiary branches) always produce two ranks of branch or spikelet primordia; these may or may not be separated by angles of 180°. doi: 10.1016/j.ydbio.2009.11.029, Pubmed Abstract | Pubmed Full Text | CrossRef Full Text, Bess, E. C., Doust, A. N., and Kellogg, E. A. Plant Sci. Res. (2009a). – ISSN 0040‐0262. Ann. 113, 931–942. doi: 10.1017/CBO9780511721816, Sokoloff, D. D., Remizowa, M. V., Linder, H. P., and Rudall, P. J. Funct. Taxonomy, phylogeny, and inflorescence development of the genus Ixophorus (Panicoideae: Poaceae). We did not observe the apical meristem. Initiation of glumes and lemmas, showing terminal spikelet (dotted lines). doi: 10.2307/2656757, Liu, Q., Oelke, E. A., Porter, R. A., and Reuter, R. (1998). Sokoloff, D. D., Remizowa, M. V., and Rudall, P. J. im, inflorescence meristem; pb, primary branch; b, bract; sm, spikelet meristem; g, glume. These are diagrammed by Vegetti and Anton (2000). LeRoux, L. G., and Kellogg, E. A. What is the difference between Racemose and Cymose? Melbourne, VIC: CSIRO. The inflorescence is terminal on the stem, so the front-back structure is not obviously related to any existing axis. J. Bot. It might also affect the hydraulic architecture of the inflorescence and thus be related to distribution of photosynthate to seeds. doi: 10.3732/ajb.89.8.1203, Edwards, E. J., and Smith, S. A. The genus Ficus (Moraceae) has an inflorescence called syconium and the genus Euphorbia has cyathia (sing. Primary branches are two-ranked and approximately distichous (C), secondary branches form on the side facing the camera. Gard. Thus, for example, we represented Paniceae with all species with published data, but Puelioideae and Bambusoideae were included even though no data are available. Morphological evolution in the graminid clade: comparative floral anatomy of the grass relatives, Flagellariaceae and Joinvilleaceae. Genet. Beitr. A new species of Centrolepis (Centrolepidaceae, Polaes) from Northern Australia, with remarkable inflorescence architecture. doi: 10.1242/dev.01441, Suzaki, T., Toriba, T., Fujimoto, M., Tsutsumi, N., Kitano, H., and Hirano, H. Y. Mol. Cresswell et al. Elymus hystrix (Figure 9). Images were either captured on Polaroid film (Harvard, UM-St. Louis) and then scanned, or captured digitally (all other sources). However, blind termination of the axis is common and occurs sporadically in the family. The inflorescence meristem thus produces floral meristems directly (Rudall et al., 2005). Appl. The inflorescence meristem of Elymus hystrix initiates broad bracts in a distichous phyllotaxis; these form in the same plane as the leaves (Figures 10A–E). This is why it is also known as an indefinite or indeterminate inflorescence. Keywords Poaceae grass evolution inflorescence References Cámara Hernández and Rúa, 1991 J. Cámara Hernández, G. Rúa, The synflorescence of Poaceae Beitr. Bot. Beitr. Attached to the lower most portion of the spikelet are two (sometimes one or none) sterile bracts called glumes . Figure 2. They may contain many flowers (pluriflor) or a few (pauciflor). Vouchers of representative specimens are listed in Table 2. The unit of its inflorescence is called spikelet. Spike – the spikelets are attached directly (sessile) to the central axis of the inflorescence (rachis), without a subtending stalk. These spikelets are variously arranged. Agrost is. Barton, M. K. (2010). The gene FLORAL ORGAN NUMBER1 regulates floral meristem size in rice and encodes a leucine-rich repeat receptor kinase orthologous to Arabidopsis CLAVATA1. Based on current data, the shift in inflorescence phyllotaxis from spiral to distichous appears to have occurred at about the same time as the expansion of genome size and shift in chromosome number that characterizes Triticeae, Bromeae, and Poeae (Grass Phylogeny Working Group, 2001; Kellogg and Bennetzen, 2004), although there is no obvious mechanistic reason why genome size per se should affect inflorescence architecture. This type of inflorescence is found in genus Euphorbia of family Euphorbiaceae; also found in genus Pedilanthus of the family. (C) Branch meristems enlarging on one side of the inflorescence. doi: 10.1111/j.1365-2435.2010.01704.x, Davis, H. G., Taylor, C. M., Lambrinos, J. G., and Strong, D. R. (2004). Plants of this species are tiny enough to fit entirely on an SEM stub (Figures 1A,B). Dorsal compression is most often found in spikelets of Panicum and related genera where a sterile floret is borne below the perfect one. Initiation of the branches is preceded by formation of large bracts that remain visible even into early development subtending the broad primary branch meristems. doi: 10.1007/s00425-005-0138-3. The basic unit of the grass inflorescence is the spikelet. doi: 10.1007/s00122-009-1151-x, Preston, J. C., Christensen, A., Malcomber, S. T., and Kellogg, E. A. Often the midrib of the lemma is extended into an awn. Res. Pollen limitation causes an Allee effect in a wind-pollinated invasive grass (Spartina alterniflora). Hepworth, S. R., Klenz, J. E., and Haughn, G. W. (2006). The inflorescence of Joinvillea is large, up to 40 cm long, and multibranched. Glyceria striata. doi: 10.1093/aob/mcs246. (2009a). In summary, we have shown that two-ranked phyllotaxis is apparently synapomorphic for the grass subfamily Pooideae, excluding Brachyelytrum, and that the two-ranked phyllotaxis gives rise to distichous phyllotaxis somewhat later in the evolution of the subfamily. (2005)] and we find that even in inflorescences that are initially distichous, the inflorescence is one-sided, developing a clear front and back. Plant Sci. (2010), Salariato et al. Phyllotaxis of primary inflorescence branches and presence of a terminal flower in the grasses; taxa in which the two-ranked inflorescence is distichous are indicated as “two-ranked (d)”. Effects of high temperatures, ash and seed position in the inflorescence on the germination of three Spanish grasses. (2009a)]. Am. J. Syst. 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