Large inflorescences increase the chance of wind pollination as well. Flowers are the seed-bearing parts of a plant, consisting of reproductive organs stamens and carpels surrounded by a brightly colored corolla petals and a green calyx sepals while inflorescence refers to the complete flower head of a plant including stems, stalks, bracts, and flowers.
Thus, this is the main difference between flower and inflorescence. Furthermore, an important difference between flower and inflorescence is that while the flower is a modified shoot, which serves as the reproductive organ of flowering plants, the inflorescence is a cluster of flowers arranged on a floral axis. Moreover, the pedicel is the stalk of the flower while peduncle is the stalk of the inflorescence.
A flower has distinct nodes and internodes while inflorescence does not show a distinct node and internodes. Hence, this is also a difference between flower and inflorescence. Another difference between flower and inflorescence is that flowers produce gametes, undergo fertilization, and form seeds while inflorescence increases the chances of cross-pollination. Some examples of flowers are roses, sunflower, etc. The flower is the individual reproductive organ of a flowering plant.
Generally, it is a modified shoot, containing a calyx, corolla, stamen, and pistil. The main function of the flower is to produce gametes, undergo fertilization, and form seeds. On the other hand, the inflorescence is a cluster of flowers.
The main stem of the inflorescence is the peduncle. A pedicel attaches each individual flower or floret into the peduncle. Moreover, inflorescence increases the chance of cross-pollination. Therefore, the main difference between flower and inflorescence is the structure and importance.
View all posts. Leave a Reply Cancel reply. Although floral maintenance of Arabidopsis can be ascribed, in part, to transcriptional repression of shoot or inflorescence identity genes by LFY , both heterozygous lfy-6 mutants and ag-1 mutants only revert when grown in SD or when ag mutations are combined with a mutation in the photoperiod pathway Okamuro et al.
One explanation for this is that LFY is only expressed at a low level in weakly inductive conditions and this may reduce its capacity to repress shoot identity genes. Okamuro et al.
Night break treatments were also effective in causing some degree of suppression. A GA-mediated signal could be a requirement for floral maintenance and might operate by promoting expression of LFY or genes downstream of LFY or by suppressing shoot identity genes.
Here, flowering time genes affect plant morphology as well as the transition to flowering. The phenotype is attributed to a deficiency of floral signals or poor competence to respond to them Poduska et al. The importance of floral signal transport has been underlined by the report that the flowering time gene CO of Arabidopsis regulates the synthesis or transport of a floral signal An et al.
The FT protein itself may move between cells or regulate synthesis of a floral signal. Gisel et al. Movement of symplastic tracer resumes on further floral development. Initial research using mixed seed giving plants with a range of flower colours indicated that Impatiens balsamina cv.
Dwarf Bush Flowered is a short day SD plant in which the majority of plants revert to leaf production when transferred to long day LD conditions Battey and Lyndon, , An association of reversion with flower colour was noted, red-flowered plants giving a completely consistent reversion response Battey, Red-flowered plants were therefore used for detailed molecular analysis of the reversion response described next.
It was also noted, however, that purple-flowered plants consistently showed continued flower development even in non-inductive LD Battey, These purple-flowered plants provided a useful resource for later physiological Tooke et al. With red-flowered plants, more short day SD cycles cause more of the flower to form before the return to leaf initiation Pouteau et al. For example, 5 SD is usually sufficient to bring about a change to whorled phyllotaxy, the loss of axillary structures, and the development of patches of pigment on bract-like leaves.
With 8 SD plants are able to develop petals before reverting. The reverted meristem, whilst producing leaves, retains some level of floral determination as the leaves are produced in whorls and without axillary meristems and rapid reflowering occurs on transfer back to inductive conditions Battey and Lyndon, A transition to a vegetative spiral phyllotaxy with associated axillary meristems is seen much later Battey, It is worth noting, however, that even under constant SD conditions, in which a complete flower is formed, the growth pattern of the meristem is only weakly determinate and reiteration from the gynoecium can occur Pouteau et al.
Vegetative expression of LFY without up-regulation upon floral induction has been described in tobacco where it is not associated with reversion Kelly et al. Physiological experiments show that reversion of Impatiens results from the failure of a leaf-derived signal to be supplied to the meristem during flower formation Pouteau et al. There is evidence to show that the meristem responds quantitatively to this leaf signal.
Whilst plants revert if deprived of the signal, reduced signal may maintain flowering, but alter the form of the flower. Restricting the number of leaves through their removal which can perceive the inductive SD conditions results in flowers which may contain up to double the number of petals of the undefoliated controls Tooke and Battey, Flower development appears to be prolonged by limited leaf-derived inductive signal; one interpretation of this is that this signal promotes the transition to C function.
In the purple-flowered line of Impatiens , plants continue to flower when transferred from SD to LD, but removal of the induced leaves those unfolded in SD causes reversion Tooke et al. This indicates that a crucial difference between the flowering purple-flowered and reverting red-flowered lines is the ability of leaves to produce an inductive signal in the absence of inductive conditions.
Thus, leaves of the flowering line deliver to the meristem a vital floral maintenance factor, either by self-perpetuation of the initial SD signal or by production of an autonomous signal in LD. In recent work, the flowering purple-flowered and reverting red-flowered lines have been crossed to address the genetic basis for this difference.
An unexpected result of this study is the appearance, in the F 1 and F 2 generations, of a novel reflowering line which neither continues to flower normally nor becomes fully reverted to ongoing leaf initiation when transferred from SD to LD Fig. The terminal flower in the reflowering phenotype is generally anomalous. Figure 4A and B show plants with prominent and numerous bract-like organs, whilst plants in Fig.
In the subtlest cases of reflowering there is little internode elongation on reversion and plants display varying degrees of phyllody before continuing flower development. A Top view of terminal flower showing flowering response.
B Top view of reverting terminal flower. A and B show the typical responses observed in the parent lines, whilst C shows a novel reflowering phenotype in some of the progeny, in which a terminal flower is produced, but after an earlier phase of floral development and reversion.
A, B Prominent and numerous bracts. C, D Terminal flowers containing numerous petals. The plant in C produced 97 petals before the first stamen. Terminal flowers which develop under SD conditions have approximately 20 petals.
However, responses are not uniform, contrasting with the parental genotypes where phenotype is invariant and true-breeding, and variation has been found between experiments F Tooke and N Battey, unpublished data.
Analysis of F 1 , F 2 and backcross progeny supports a single gene hypothesis as the simplest explanation for the observed phenotypes. Under this hypothesis the parent flowering line is AA and the reverting line, aa. The heterozygous genotype Aa has the novel reflowering phenotype but is leaky so that some of this genotype flower or, less frequently, revert. The effects of gene A appear to be dosage-dependent such that AA plants are largely unaffected by the switch from SD to LD; Aa plants undergo a brief reversion period then reflower and aa plants revert completely.
Although the parent purple- and red-flowered lines are consistent in their flowering and reverting responses, their F 2 progeny show clearly that flower colour and reversion response are not genetically linked.
Therefore, in the F 2 generation, whilst a plant may be of genotype aa, the flower colour would not necessarily be red. When combined with the previously described data on leaf signalling in purple- and red-flowered Impatiens Pouteau et al. In the absence of this function, the signal fails to reach the meristem in non-inductive conditions. Consistent with this, the purple-flowered line of Impatiens that continues to flower in non-inductive LD unless its leaves are removed can flower eventually in LD, whereas the SD requirement is absolute in the red-flowered line.
Thus the occurrence of reversion in LD correlates with an inactive daylength-independent pathway. This interpretation leads to the conclusion that, in Impatiens , floral commitment is a consequence of continued supply of leaf-derived floral signal to the meristem see also Hempel et al. But can this conclusion, that floral commitment is leaf-derived, be applied generally to other species?
One possibility is that the susceptibility of Impatiens to revert in such a clear-cut manner results from the loss of floral signal combined with a peculiarity in the downstream, flower development process. Thus, in most other species a large number of interacting pathways give a generalized stability to flowering that leads to commitment or determination.
A process with such a high degree of molecular redundancy may be inherently difficult to reverse once it has been initiated. Floral commitment may therefore be different in character from stable epigenetic changes that occur in plant development, such as vernalization. The underlying regulation of vernalization is now being revealed, and it is clearly brought about in a highly specific way Gendall et al.
If this interpretation is correct, the failure of Arabidopsis to revert completely i. In Impatiens it appears that a leaf-derived signal constantly regulates floral development at the meristem.
The question that this analysis begs, however, is why floral development in Impatiens is so dependent on the leaf signal. This is discussed further in the Conclusions section of this review.
Strong evidence that a leaf-derived signal controls flowering in Zea mays is provided by the id1 mutant which is late flowering and displays vegetative characteristics in the inflorescence Colasanti et al.
The ID1 gene is only expressed in immature leaves, yet controls flowering at the meristem. This suggests that it plays a role in the synthesis or transport of a leaf-derived signal which induces and maintains flowering. Flower initiation in Pisum occurs when a threshold promoter:inhibitor ratio is exceeded through the activity of several independent loci Murfet, ; Weller et al.
A fine balance exists though, and reversion can be observed in one specific genotype lf E Sn. Flowering is followed to varying extents by reversion and then a subsequent stable floral state.
The shifting promoter:inhibitor dynamics within the plant as, for example, the scion grows larger or the inhibitory potential decays as the plant ages could explain this result Murfet, If reversion is considered to result from a lack of determination commitment in meristem developmental fate Huala and Sussex, , evidence on the general character of the determination process is relevant to it.
Determination can be tested through experiments involving propagation of the plant, bud, meristem or cell in question, away from conditions or signal sources that induce inflorescence or floral fate Huala and Sussex, Irish and Nelson have shown that the determination of inflorescence meristems can occur separately from that of flower primordia.
Zea mays inflorescence meristems grown in vitro produced indeterminate vegetative structures with inflorescence phyllotaxy. Unless floral organ development had been initiated before isolation, meristems did not continue with normal flower tassel development. From this and related work it has become necessary to define a meristem by its phyllotaxy and other growth patterns and not the identity of organs it produces Irish and Nelson, ; Huala and Sussex, For individual cells, determination can occur in a completely isolated meristem, in a meristem surrounded by a critical number of primordia, or outside the meristem e.
Nicotiana stem segments Singer and McDaniel, ; Ferguson et al. These results indicate that determination can occur at plant, meristem, primordium, and cell even non-meristem cell level with different requirements for each type of organizational unit or plant species.
This could account for the organ mosaics observed in Impatiens and Arabidopsis in response to environmental and genetic manipulation, respectively Battey and Lyndon, , ; Ng and Yanovsky, In vitro work has led to the suggestion that, in environment-responsive plants, non-reversion could be a result of the plants' capacity to prevent flowering in weak inductive conditions Donnison and Francis, In this case, plants only flower when a threshold amount of signal has been received by the meristem.
The timing of this event has been determined through in vitro meristem culture experiments in Lolium temulentum McDaniel et al. Suboptimal signal levels do not result in reversion but rather slower flowering and abnormal flowers. In plants following this pattern, intact meristems flower after evocation and determination has been achieved so they do not revert when transferred to non-inductive conditions. Work with Silene coeli-rosa Donnison and Francis, suggests that there is another group of environment-responsive plants that do not normally revert, but do show reversion when the meristem is isolated from the plant.
This observation is taken to indicate the continued need for signals from the whole plant for complete flowering. Floral determination occurs sequentially in the different whorls. Insufficient induction in these plants results in reversion after the last determined whorl. It has been suggested that intact meristems in these plants may not be permanently committed to flowering, but do not revert in non-inductive conditions because of a consistent supply of signals from the leaves.
In environment-neutral plants like Nicotiana tabacum and Zea mays , in vitro studies have shed light on the effect of age and node number on meristem phase change from juvenile to adult or vegetative to reproductive Irish and Nelson, ; Irish and Jegla, The leaves act as a source of determination signal to the apical meristem and this signal is constantly necessary up to a certain stage.
Meristems not receiving enough signal from the leaves or cultured too early will revert to juvenile or vegetative growth Irish and Jegla, Reversion requires of the plant a flexibility to switch from floral to vegetative or inflorescence development.
The latter two are a form of reversion from flowering which tends to occur at the end of the season Wang and Cronk, How is this flexibility achieved? One explanation could be that a subset of cells in the meristem retains an undifferentiated or vegetative identity which is reasserted on reversion. Another is that cells which are initially assigned a floral fate regain the ability to become vegetative. In the Arabidopsis lfy-6 mutant described earlier in situ hybridization experiments, designed to analyse the origin of the ectopic shoot, reveal that cells of the meristem and even some of those in the growing ectopic shoot express the floral organ identity gene AG.
This implies that cells that are initially floral are reprogrammed during reversion Okamuro et al. This form of reprogramming may take place at a very subtle level. Hempel et al. Zea mays ifa1 mutants suffer a loss of determinacy of all the usually determinate meristems spikelet pair, spikelet, floral meristems Laudencia-Chingcuanco and Hake, and in these plants KN1 expression reappears in a group of cells in the centre of the ovule.
Thus meristematic fate appears to be regained at a molecular level. In the first model, the lack of FBP2 means that floral commitment is slow to become established and the floral transition is incomplete, with some cells retaining inflorescence identity. An alternative model is that a floral meristem forms but the lack of FBP2 results in a flower in which the inflorescence character is not completely suppressed Angenent et al.
Whilst wild-type expression is confined to vegetative development, heterologous expression in Nicotiana tabacum results in phenotypic alterations to the flower, for example, longer internodes in the inflorescence, sepals replaced by leaves Garcia-Morato et al.
A common theme to these molecular reports is that floral maintenance is achieved through repression of vegetative or inflorescence development, suggesting that these forms of development are a type of default pathway onto which flowering may be superimposed.
This coexistence of vegetative and floral development is interpreted as a loss of an abrupt transition between the two phases of development. In ifa1 mutants see above , however, reversion is always to a distinct, specific and not mixed meristem type Laudencia-Chingcuanco and Hake, One of the outstanding problems for plant developmental biologists is to provide a mechanistic account of life-history strategy.
The regulation of individual developmental events, such as flowering, fruiting, and senescence is now relatively well-understood; so is the metabolic regulation that underpins day-to-day plant existence. But the correlative controls that connect these two levels, and are so characteristic of plants Woolhouse, ; Hensel et al. Viewed in this context, flowering of an individual meristem becomes part of a wider process, in which the fate of the whole plant is determined.
In an annual such as Arabidopsis , flowering is irreversible, global, and leads to fruiting and plant death. The species is therefore monocarpic. Some ecotypes with a high vernalization requirement can behave as winter annuals, or biennials if spring-sown Michaels and Amasino, Nevertheless, flowering still results in plant death. The majority of plant species, however, are perennial: flowering occurs locally and is associated with the senescence and death of only part of the individual Battey and Tooke, Crucially, some meristems do not adopt a floral fate and therefore provide the basis for continued growth the next season.
This polycarpic life-history requires global controls over meristem behaviour and organ development that are currently not well understood. Does reversion, allowing a return to the vegetative mode after flowering, have any relevance to life-history strategy?
There is little evidence that flower reversion has adaptive significance; it seems just to be a developmental abnormality. Inflorescence reversion, however, can provide a means for the individual axes of a plant to switch repeatedly between vegetative and reproductive development. An interesting example of this is the Ravenelle wallflower Diomaiuto, Thus inflorescence reversion provides a mechanism for ensuring a polycarpic perennial life-history in this species.
In a similar way, individual shoots of the bottlebrush plant Callistemon revert to vegetative growth after the inflorescence phase, so that the form of the plant shows the history of successive flowering phases Fig. In another member of the Myrtaceae, Metrosideros , it has been proposed that the attainment of reproductive competence is a consequence of the tree reaching a certain degree of branching complexity Clemens et al. Extreme branching complexity, however, leads to a reduction in the number of vegetative meristems and this threatens the capacity of the tree for further growth.
In this situation, inflorescence reversion to vegetative growth occurs with increased frequency to generate new vegetative capacity Sreekantan et al. In this case, reversion emerges as an important mechanism for maintaining the balance between vegetative and reproductive development in the polycarpic perennial life-history strategy of the tree. The crucial question in these examples of inflorescence reversion is: what is the nature of inflorescence identity? Is the inflorescence meristem different from the vegetative meristem in an important functional sense, in which case the floral fate of its axillary meristems would be a consequence of its altered developmental trajectory?
Or is it just a meristem protected from adopting a floral fate? Based on studies with Arabidopsis Bradley et al. Flowering leads to sexual reproduction of the plant; yet in some cases this outcome to the flowering process is not inevitable and is under environmental control.
Pseudovivipary is a form of inflorescence proliferation in which the flowering process is aborted and further development produces leafy shoots or bulbils. Pseudovivipary, therefore, provides an alternative means to reproduce. This asexual adaptation is particularly prominent in species growing in extreme environments. It is found in the recently glaciated areas of the Northern hemisphere and high latitudes in the Southern hemisphere Moore and Doggett, Around 1. Species which show pseudovivipary are generally perennials and very often grasses, for example, Festuca vivipara , Poa alpina vivipara , Deschampsia alpina Molau, ; Elmqvist and Cox, Late-flowering can also be a factor and may be a key to the developmental process and its advantages.
In studying reproductive strategies of Tundra plants, Molau suggests that late-flowering makes time a limiting resource. Many mechanisms for outbreeding e.
These late-flowering plants take a seed-risking selfing rather than a pollen-risking dispersal strategy Molau, Expanding this idea, vegetative reproduction, by means of reversion to leafy shoot production, could be viewed as further insurance of successful reproduction. As Latting suggests, pseudovivipary offers a means to cope with short growing seasons by allowing rapid plant establishment. In developmental terms there are two main ways in which pseudovivipary occurs; proliferation may be achieved by lemma elongation to form the first leaf of the plantlet, as is the case in Deschampsia , or by transformation of the spikelet to a leafy shoot Festuca ovina , Poa alpina , Poa bulbosa Moore and Doggett, In grasses showing pseudoviviparous development it is induced by marginal LD induction, i.
In some cases it has been assimilated as a heritable response, but it is not usually an irreversible pattern of development beyond environmental influence Evans, Habitually pseudoviviparous grasses can be induced to flower although flowering is not completely normal given optimal inductive conditions Heide, Since floral initiation can occur, meristem competence to respond to floral promotion appears to be established.
It is the promotion of the shift towards floral development which appears weak. There are similarities here with the reversion of Impatiens balsamina. Given optimal inductive conditions continuous SD , Impatiens will flower and produce seed yet, even as it does so, the ability to proliferate is evident in the reiterative growth of the gynoecium. Abandoning flowering to produce a leafy shoot is the result of weak induction.
Perhaps, as proposed for Impatiens , pseudoviviparous development is a feature of plants lacking sufficient genetic redundancy to commit the plant to flowering.
Here, the vulnerability of floral development to environmental conditions ensures flowering always results in reproduction, either sexual or asexual. The recent studies of flowering of Arabidopsis thaliana have been a guide to the principal components of the reversion process and have presented clear models of how floral maintenance might be achieved.
Interestingly, reversion of Arabidopsis is never a complete return to vegetative development. The relative difficulty of obtaining reversion, and the residual floral characteristics when it does occur may be a consequence of the genetic redundancy in flowering pathways of this plant. AP1 , Hempel et al. In fact, the single gene mutations in Arabidopsis giving rise to reversion to inflorescence development do so only when plants are grown in weakly-inductive SD conditions.
In Impatiens balsamina , genetic analysis of a red-flowered line which reverts to vegetative development, and a purple-flowered line which maintains flowering when removed from inductive conditions, suggests that a single gene controls these different responses.
Evidence from Impatiens contributes to the continuing physiological question as to the site of regulation of floral commitment. Axillary inflorescence: when flower is found in the axil of a leaf. It may be of following types: Racemose, Cymose, Mixed and Special.
Example: Callistemon. Significance of Inflorescence. Provides chance for cross pollination. Make flowers more conspicuous thus insects attract towards it. Large inflorescence enhance the chance of wind pollination. Flower vs Inflorescence. You might like Show more. Unknown 3 May at Unknown 18 May at Unknown 23 September at
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