The Origin of the Inflorescences of Xanthium

Farr, Clifford H.

doi:10.1086/331507

Cited by 9 publications

(8 citation statements)

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“…EVALUATION OF RESPONSE: Although investigations of photoperiodic responses have generally been reported in terms of the presence or absence of flower primordia, proper evaluation of the results reported here demanded a graduated measure. It was obvious from previous reports (9,15) and from preliminary dissections that the development of the inflorescence of cocklebur was not an all or none affair and that the amount of floral development in a given time depended upon the level of the initial stimulus that initiated it. Thus, it was decided to divide the development of the inflorescence into several easily identifiable stages.…”

Section: Methods and Resultsmentioning

confidence: 98%

“…The exudation and subsequent resorption of a drop of liquid pulls the grain through the micropyle to the surface of the nucellus where the grain develops a pollen tube directed into the nucellar tissue. Growth ceases over the winter but resumes again the following spring when the pollen tube completes its passage through the nucellus into the neck of an archegonium where it ruptures, releasing the stalk cell and the tube and sperm nuclei (1,3,4,9,13). During this year of life the pollen grain develops a relatively long tube and presumably respires actively except for the cold winter months.…”

Section: Literature Citedmentioning

confidence: 99%

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Photoreversibility of Flower Initiation.

Downs

1956

Plant Physiol.

113

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Action-spectrum studies have shown that such diverse light-controlled plant responses as flower initiation (1,17,18), internode elongation (2,8,19), leaf expansion (8,19), and seed germination (4,23) the dark period, two short-day plants, soybean (Glycine Max (L.) AMerr. var. Biloxi) and pigweed (Amaranthus caudatus L.), and two long-day plants, barley (Hordeum vulgare L. var. Wintex) and Hyoscyamus niger L., were tested for evidence of the far-red action. A brief irradiation near the middle of an inductive dark period of 13 hours for soybean and 12 hours for pigweed prevented initiation of flowers, whereas a similar interruption near the middle of a non-inductive dark period of 12.5 hours for barley and 12 hours for Hyoscyamus induced flowering. In each case a far-red irradiation immediately following the dark-period interruption with red reversed the effect of the red light (table I).PLANT 'MATERIALS: Studies into the details of the photoreversible reaction controlling flower initiation were conducted principally with the short-day plants cocklebur, Xanthium pensylvanicum Wallr. (X. saccharatum Wallr.) and Biloxi soybean.There is considerable confusion arising from personal variations in the choice of the specific name for this species of Xanthium. Wallroth (24) described X. pensylvanicum and X. saccharatum as distinct species and published his descriptions in the same journal on the same date. According to Section 10 of the

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Section: Methods and Resultsmentioning

confidence: 98%

Section: Literature Citedmentioning

confidence: 99%

Photoreversibility of Flower Initiation.

Downs

1956

Plant Physiol.

113

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“…consists of only two flowers and is borne in the axil of a bract, \vhich should be considered as the inflorescence bract. I t is surrounded by a \vIlorl of involucral bracts, as described by Farr (1915), which do not, however, persist but fall oif a t the fruiting stage.…”

Section: Observationsmentioning

confidence: 98%

Morphology of the Bur of Xanthium

Trivedi¹,

Sharma²

1964

Can. J. Bot.

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,I his communication reports on an anatonrical stucly of Sanlh%zitt~. slri~?t~arit~nr I.iri~i., \vilh respect LO the rcccp~acle, the b~~r , its spil~es, ailcl septum between the t\vo HOIVC~S of a fc~nale inHoresce11ce. T h e ali:~tomical cletails, prcsen~ecl herc, SLIP POI.^ i::1rr1s vie\\) (l915), \\.hich \\.as b;isctl cnrirely on ontogenical s t~~d i c s , ihat thc b i~r is a cotitin~~alion ol the receptacle, and that the spines it carries arc i~~oclilied floral bracrs. Observations'The female inflorescence of Xnqztl~iz~nz s t r~~m a r i z~m Linn. consists of only two flowers and is borne in the axil of a bract, \vhich should be considered as the inflorescence bract. I t is surrounded by a \vIlorl of involucral bracts, as described by Farr (1915), which do not, however, persist but fall oif a t the fruiting stage. Vascz~lar AnatomyThe inflorescence of Xanthium is attached to the axis by a large base, which is considered to be the receptacle. A transverse section passing through

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Section: Introductionmentioning

confidence: 97%

“…However, most studies were devoted to the initiation and development of the terminal staminate inflorescence, and little is known about the formation of the lateral pistillate inflorescences. Their gross morphological and anatomical development has been described in a few studies (4,8,9,12), and fragmentary physiological aspects have been considered in some other reports (12,13,19,20).The available information on factors that affect sex expression in cocklebur is also very scarce. Effects of photoperiod (12) and nutrition (13) have been described, and it was reported that exogenous GA3 decreased the male to female ratio in a dayneutral strain (21).…”

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confidence: 99%

Flowering in Xanthium strumarium

Leonard¹,

Kinet²,

Bodson³

et al. 1981

Plant Physiol.

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Vegetative plants of Xanthium strumarium L. grown in long days were induced to flower by exposure to one or several 16-hour dark periods. The distribution of male and female inflorescences on the flowering shoot was described, and a scoring system was designed to assess the development of the female inflorescences. The time of movement of the floral stimulus out of the induced leaf and the timing of action of high temperature were shown to be similar for both the apical male and lateral female inflorescences.Strong photoperiodic induction of the plants favored female sex expression, while maleness was enhanced by exogenous gibberellic acid. The problem of the control of sex expression in Xanthium is discussed in relation to the distribution pattern of male and female inflorescences on the flowering shoot and to the state of the meristem at the time of the arrival of the floral stimulus.Flowering in the Chicago strain of Xanthium strumarium L., an absolute short-day plant, has been extensively investigated (16,18). However, most studies were devoted to the initiation and development of the terminal staminate inflorescence, and little is known about the formation of the lateral pistillate inflorescences. Their gross morphological and anatomical development has been described in a few studies (4,8,9,12), and fragmentary physiological aspects have been considered in some other reports (12,13,19,20).The available information on factors that affect sex expression in cocklebur is also very scarce. Effects of photoperiod (12) and nutrition (13) have been described, and it was reported that exogenous GA3 decreased the male to female ratio in a dayneutral strain (21).The aim of the present work was to start a comparative physiological study of the initiation and development of the male and of the female inflorescences in the Chicago strain of cocklebur. Since GA is known generally to increase the tendency to maleness when applied to monoecious and dioecious plants (5) Application of GA3. GA3 was applied in aqueous 0.3 mm solution by spraying the whole plants to run off with a hand atomizer. In preliminary experiments, this concentration was found to give the optimal effect on sex expression, and this application method was found to be superior to spraying only the sole, half-expanded leaf or treatment of the roots by watering or of the shoot apex by application with a small cotton plug. Control plants were sprayed with distilled H20. Tween 20 (polyoxyethylene-sorbitan monolaurate; 0.1%) was present in all solutions as surfactant.Recording Methods. The main axis and side axes of the plant were considered. The side axes were numbered acropetally from the induced leaf (Fig. 1). On the basis of the sex of the terminal inflorescence of the side axes, the whole flowering shoot can be divided into three zones ( Fig. 1) In studies of initiation and development of the female inflorescence, the terminal bud of the side axes 8 and 9, which generally produced a pistillate inflorescence, were dissected 40 days after the start ...

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The Origin of the Inflorescences of Xanthium

Cited by 9 publications

References 0 publications

Photoreversibility of Flower Initiation.

Photoreversibility of Flower Initiation.

Morphology of the Bur of Xanthium

Flowering in Xanthium strumarium

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