The reproductive biology of boreal forest herbs. I. Breeding systems and pollination

1987 ◽  
Vol 65 (10) ◽  
pp. 2036-2046 ◽  
Author(s):  
Spencer C. H. Barrett ◽  
Kaius Helenurm
Keyword(s):  
Boreal Forest ◽  
Reproductive Biology ◽  
Fruit Set ◽  
Experimental Studies ◽  
Reproductive Mode ◽  
Breeding Systems ◽  
Cornus Canadensis ◽  
Forest Herbs ◽  
Maianthemum Canadense ◽  
Floral Syndromes

Detailed observations and experimental studies of the reproductive biology of 12 boreal forest herbs were conducted over a 3-year period (1978–1980) in spruce–fir forests of central New Brunswick. The species examined were Aralia nudicaulis, Chimaphila umbellata, Clintonia borealis, Cornus canadensis, Cypripedium acaule, Linnaea borealis, Maianthemum canadense, Medeola virginiana, Oxalis montana, Pyrola secunda, Trientalis borealis, and Trillium undulatum. All taxa are insectpollinated perennials and most exhibit clonal growth. Floral syndromes of the understory community are relatively unspecialized with many species possessing small white or green flowers. A total of 103 taxa of insects were collected from flowers during the 1979 season. Bombus spp. are the major pollinators of 5 of the 12 species. Syrphid flies, bee flies, and halictid and andrenid bees were also commonly observed. Controlled pollinations were undertaken to determine the breeding systems of herbs. Bagged, self-, cross- and open-pollinated treatments were used to investigate the capacity for self-pollination, compatibility status, and factors influencing fecundity in each species. A diversity of reproductive systems was revealed. Six species are completely dependent on insects for pollination, four species are weakly autogamous, one is strongly autogamous, and one appears to be apomictic. Comparisons of fruit-set and seed set from controlled self- and cross-pollinations indicate that four species are strongly self-compatible, one is dioecious, and the remainder display varying degrees of self-incompatibility. Despite this variation, outbreeding appears to be the most common reproductive mode. In several species there is evidence that low pollinator service limits fruit-set.

The reproductive biology of boreal forest herbs. II. Phenology of flowering and fruiting

1987 ◽  
Vol 65 (10) ◽  
pp. 2047-2056 ◽  
Author(s):  
Kaius Helenurm ◽  
Spencer C. H. Barrett
Keyword(s):  
Boreal Forest ◽  
Fruit Set ◽  
Pollen Limitation ◽  
Fruit Production ◽  
Fruit Removal ◽  
Cornus Canadensis ◽  
Forest Herbs ◽  
Pollinator Service ◽  
Maianthemum Canadense ◽  
Major Factors

The flowering and fruiting phenologies of 12 boreal forest herbs were recorded during 1979 (flowering and fruiting) and 1980 (flowering only) in spruce–fir forests of central New Brunswick. The species studied were Aralia nudicaulis, Chimaphila umbellata, Clintonia borealis, Cornus canadensis, Cypripedium acaule, Linnaea borealis, Maianthemum canadense, Medeola virginiana, Oxalis montana, Pyrola secunda, Trientalis borealis, and Trillium undulatum. Flowering in the community occurred from mid-May to the end of July. The order of flowering was maintained in the 2 years, but the degree of synchronization of inflorescences differed in several species. Fruiting in the community began in mid-July and extended beyond the end of September. The percentage of buds that ultimately bore fruit ranged from 0 (Cypripedium acaule) to 61% (Aralia nudicaulis). With the exception of Cypripedium acaule, which received little pollinator service, the self-incompatible species, Cornus canadensis, Maianthemum canadense, and Medeola virginiana, experienced the lowest levels of fruit-set. Pollen limitation and predation of developing fruit appear to be the major factors limiting percentage fruit-set in boreal forest herbs. Fruit production varied with time of flowering of inflorescences in several species, with periods of low fruit-set tending to coincide with lower densities of flowering inflorescences. Significant rates of fruit removal by herbivores occurred in all sarocochorous species. Disappearance of fruits from infructescences ranged from 31 (Medeola virginiana) to 95% (Aralia nudicaulis), with highest removal rates occurring during periods of greatest fruit availability.

The neutralisation of acid rain by the leaves of four boreal forest species

1988 ◽  
Vol 66 (9) ◽  
pp. 1877-1882 ◽  
Author(s):  
B. A. Gaber ◽  
T. C. Hutchinson
Keyword(s):  
Boreal Forest ◽  
Acid Rain ◽  
Cell Walls ◽  
Leaf Surface ◽  
Weather Conditions ◽  
Cornus Canadensis ◽  
Exchange Processes ◽  
Rapid Changes ◽  
Maianthemum Canadense ◽  
Rate Of Evaporation

A field study was carried out in the boreal forest of Ontario to measure the neutralisation response of the leaves of Cornus canadensis, Aralia nudicaulis, Maianthemum canadense, and Acer spicatum to simulated acid rain. Plots of each species were sprayed with pH 5.6, 3.8, or 3.2 rain, and the pH of the raindrops on the leaves and on Parafilm (control) was measured with a microelectrode at 15-min intervals until the leaves dried. Species differed in their ability to neutralise the rain, with C. canadensis consistently neutralising acidic raindrops the most. The neutralisation response varied greatly between pH treatments, with greatest neutralisation occurring at the most acidic pH treatment. Raindrop neutralisation primarily took place within the first few minutes following the spray. For this reason, the dissolution of basic particulates on the leaf surface was probably responsible for the rapid changes in raindrop pH, while slower changes may reflect cation exchange processes with the cell walls. Weather conditions determined the rate of evaporation of the raindrops, and this affected their acidity. High rates of evaporation reduced the time available for leaf surface – raindrop interactions and are probably responsible for the acidification observed in some plots.

Reproductive biology of Monttea aphylla (Scrophulariaceae)

2011 ◽  
Vol 59 (8) ◽  
pp. 713 ◽  
Author(s):  
Mariana Tadey
Keyword(s):  
Reproductive Biology ◽  
Fruit Set ◽  
Flowering Phenology ◽  
Fruit Production ◽  
Generalist Species ◽  
Monte Desert ◽  
Distributional Range ◽  
Pollinator Assemblage ◽  
Oil Flowers ◽  
Floral Syndromes

Monttea aphylla is an aphyllus shrub abundant in the Monte Desert, Argentina. This species presents particular floral syndromes including violet, tubular flowers with trichome elaiophores that produce oil. Oil flowers are associated with specialised bees with an oil-collecting apparatus. To better understand the reproductive biology of M. aphylla, the mating system, flowering phenology, the associated pollinator assemblage and foraging behaviour was determined at the southern-most part of its distributional range. Results were compared with those of previous studies and discussed. At this southern location M. aphylla is a self-incompatible species; it relies on pollinators for fruit production and presented a low fruit set. Flowering occurred during the spring, from October to December. M. aphylla was pollinated by three species of bees (Apidae); two generalist species (Centris brethesi and Mesonychium jenseni) and one specialist to M. aphylla (Centris vardyorum). M. jenseni is a cleptoparasite of Centris species. Centris species are oil-collecting bees and showed territorial behaviour (i.e. they always visited a restricted group of plants which they protected from other visitors), they visited several flowers/plants, which enhanced geitonogamous self-pollination and reduced pollination efficiency, and which might explain the low natural fruit set observed in M. aphylla. C. vardyorum was the most important pollinator of M. aphylla in the study area. The reproductive biology of M. aphylla differs along its distributional range. Apparently, southern populations of M. aphylla are more specialised than the northern populations, the former being pollinated by a few related pollinator species whereas at the northern location a variety of visitors were observed.

EFFECTS OF A SPLIT APPLICATION OF SEVIN-4-OIL® ON POLLINATORS AND FRUIT SET IN A SPRUCE–FIR FOREST

1984 ◽  
Vol 116 (3) ◽  
pp. 457-464
Author(s):  
Richard W. Hansen ◽  
Eben A. Osgood
Keyword(s):  
Fruit Set ◽  
Spruce Budworm ◽  
Split Application ◽  
Cornus Canadensis ◽  
Native Bee ◽  
Maianthemum Canadense ◽  
Pollinator Populations

AbstractCounts of four pollinating insect groups were taken in unsprayed forest localities and in areas sprayed with a split application of Sevin-4-oil® (carbaryl) for spruce budworm control. Results indicate a reduction of pollinator populations due to spraying.Fruit set, measured by fecundity ratios (fruits/flower), was determined for Cornus canadensis L., Maianthemum canadense Desf., Clintonia borealis (Ait.) Raf., and Viburnum cassinoides L. in sprayed and unsprayed areas. Fecundity values for C. canadensis and M. canadense were significantly lower in sprayed than in unsprayed areas. Fruit set of C. borealis was apparently unaffected by carbaryl spraying, but the seed/flower ratio was significantly reduced in the sprayed area. V. cassinoides fecundity values were unaffected by carbaryl application. Reductions in native bee populations probably had the greatest impact on fruit set.

Chemical changes in simulated raindrops following contact with leaves of four boreal forest species

1988 ◽  
Vol 66 (12) ◽  
pp. 2445-2451 ◽  
Author(s):  
Brigitte A. Gaber ◽  
Thomas C. Hutchinson
Keyword(s):  
Boreal Forest ◽  
Dry Deposition ◽  
Ion Concentration ◽  
Forest Species ◽  
Ion Concentrations ◽  
Cornus Canadensis ◽  
Rapid Changes ◽  
Maianthemum Canadense ◽  
Forest Plant Species

Simulated raindrops of pH 5.6 or 3.2 were sprayed on four boreal forest plant species in situ, and raindrops were subsequently collected from their leaves for chemical analysis. The purpose was to understand better the changes involved in foliar neutralisation of acidic raindrops. The species used were Cornus canadensis, Aralia nudicaulis, Maianthemum canadense, and Acer spicatum. Samples were analysed for Ca2+, Mg2+, Na+, K+, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], Cl−, and F−, as well as pH. Changes in leaf raindrop ion concentrations were greater when sprayed with the pH 3.2 than with the pH 5.6 rain. Both increases and decreases in ion concentration were found, indicating leaching and (or) dissolution of particulates on the leaf or retention by the canopy, respectively. Rapid changes in ion concentrations suggest surface deposits play an important role in leaf raindrop neutralisation. Increases in [Ca2+] and [Mg2+] in raindrops with greater neutralisation are evidence that cation exchange may also be occurring (r2 = 0.170 and 0.321, respectively, at pH 3.2; p < 0.01). There were significant negative correlations between changes in [H+] and changes in[Formula: see text], [Formula: see text], and [Formula: see text] (r2 = 0.562, 0.525, and 0.297, respectively, at pH 3.2;p < 0.01). Most of the other ions measured also showed significant correlations with changes in [H+], but generally the correlation could account for only a small percentage of the observed results (low r2). Dry deposition was also measured.

scholarly journals Pollination and Breeding System of Lowbush Blueberries, Vaccinium angustifolium Ait. and V. myrtilloides Michx. (Ericacaeae), in the Boreal Forest

2005 ◽  
Vol 119 (1) ◽  
pp. 48 ◽  
Author(s):  
Masayuki Usui ◽  
Peter G. Kevan ◽  
Martyn Obbard
Keyword(s):  
Boreal Forest ◽  
Fruit Set ◽  
Frost Damage ◽  
Fruit Production ◽  
Breeding Systems ◽  
Vaccinium Angustifolium ◽  
Cross Pollination ◽  
Different Ages ◽  
Canadian Boreal Forest ◽  
Pollination Systems

Breeding systems and pollination requirements of two wild lowbush blueberries, Vaccinium angustifolium and V. myrtilloides, in the Canadian boreal forest in the Chapleau Crown Game Preserve, Ontario, were tested. Fruit production, size and seediness were significantly higher in samples exposed to natural pollination than in those cross- or self-pollinated by hand. There were no significant differences among artificial treatments (variously hand-pollinated and bagged) except when cross-pollination (xenogamy) was done by insect pins. In V. angustifolium, the density of flowering varied with forest age (canopy closure). It was most in open areas and least in the sites with the most mature forest. Although fruit-set and seediness varied among forest habitats of different ages, there were no significant differences between sites in forests of different ages. Thus, pollination seems to be similarly effective no matter the age of the forest. In both species, fruit-set in 1992, which had severe June frosts, was markedly poorer than that in 1993 when the flowers suffered little frost damage. The combined number of complete and incomplete seeds from the fruit among the breeding and pollination systems tested were similar; however, the ratio of complete seeds to total seeds was greater from cross-pollinated than from self-pollinated flowers. Our observations indicate that there is little natural fruit-set without insect-mediated cross-pollination and that cross-pollination provides much better fruit and seed-set than does self-pollination.

Ecology, reproductive biology and hybridization in Gaultheria L.

1991 ◽  
Vol 48 (1) ◽  
pp. 81-89 ◽  
Author(s):  
David J. Middleton
Keyword(s):  
Morphological Change ◽  
Reproductive Biology ◽  
Fruit Set ◽  
Male Sterile ◽  
Fleshy Fruits

The ecology, reproductive biology and hybridization of species in the genus Gaultheria (Ericaceae) has been investigated with particular reference to those species in Ecuador. Most species were found to be plants of disturbed ground particularly on roadside banks and forest margins. The species in Ecuador were not seen to be visited by potential pollinators although fruit set was high. No animals were seen to eat the fleshy fruits. Male sterile plants of many species from throughout the distribution of the genus were observed indicating a higher level of gynodioecism in the genus than previously thought. Empty anthers in two Ecuadorean species suggests that gynodioecism may be present in many species without any clear morphological change. A hybrid between Gaultheria myrsinoides and G. reticulata has been found in Ecuador.

Plant-level fecundity and andromonoecy in three common (Melaleuca styphelioides, M. thymifolia, M. nodosa) and one rare (M. deanei) Melaleuca (Myrtaceae) species of the Sydney region

2014 ◽  
Vol 62 (4) ◽  
pp. 276 ◽  
Author(s):  
Alison Hewitt ◽  
Paul Holford ◽  
Adrian Renshaw ◽  
Anthony Haigh ◽  
E. Charles Morris
Keyword(s):  
Reproductive Performance ◽  
Fruit Set ◽  
Seed Set ◽  
Low Frequency ◽  
Common Species ◽  
Flowering Plants ◽  
Breeding Systems ◽  
Small Populations ◽  
Small Field ◽  
Plant Level

This paper reports plant-level measures of reproductive performance from large and small field populations of the vulnerable species Melaleuca deanei F.Meull. compared with three common species within the genus: Melaleuca nodosa (Sol. ex Gaertn.) Sm., Melaleuca thymifolia Sm. and Melaleuca styphelioides Sm. Measures reported include average seed numbers per capsule and per plant; average fruit loads per plant; the proportion of buds that become flowers and thence fruits (fruit set); the number of ovules per flower and seed : ovule ratios (seed set); and floral morphologies. Results indicate that when M. deanei flowers, bud to flower ratios and flower to fruit ratios are not reduced compared with the congeners or between large and small populations. Seed loads per plant held by fruiting plants were comparable between the species and between large and small populations of M. deanei. Seed to ovule ratios were in the order of 5–9% in M. nodosa; 5–7% in M. styphelioides; 7–10% in M. deanei; and 12–15% in M. thymifolia. Larval herbivory of ovules was recorded in M. nodosa and pre-dispersal seed predation noted in M. thymifolia. Andromonoecy was recorded in two of the species at rates of 0.9–3.1% (M. deanei) and 2.9–7% (M. thymifolia). Results suggest that seed production within smaller populations of M. deanei is poor because of a low frequency of flowering and a low proportion of flowering plants per population, rather than plant-level pollination, fruit- or seed-set barriers. Further study is needed to determine the triggers to flowering, the breeding systems, the extent of clonality and the germination and establishment requirements in these species.

Very Low Fruit : Flower Ratios in Grevillea (Proteaceae) are Independent of Breeding System

1998 ◽  
Vol 46 (4) ◽  
pp. 465 ◽  
Author(s):  
Luise Hermanutz ◽  
David Innes ◽  
Andrew Denham ◽  
Robert Whelan
Keyword(s):  
Fruit Set ◽  
Pollen Limitation ◽  
Breeding Systems ◽  
Mature Fruit ◽  
Closely Related Species ◽  
Woody Perennials ◽  
The Family ◽  
Self Compatibility ◽  
Species Specific

Members of the family Proteaceae have extremely low mature fruit : flower (FR : FL) ratios (range 0.001–0.163) compared with other temperate, hermaphroditic, woody perennials. Sutherland’s (1986) survey of FR : FL ratios indicated that compatibility was an important factor explaining levels of fruit set. The role of compatibility in regulating FR : FL ratios was tested in five closely related species of Grevillea (Proteaceae). Species-specific compatibility was compared using the self-compatibility index (SI = ratio of selfed fruit set to crossed fruit set) calculated at fruit initiation to minimise the confounding effect of other post-fertilisation fruit losses, such as inbreeding depression and pre-dispersal predation. Fruit : flower ratios at initiation ranged from 0.041–0.249, and at maturity 0.015–0.096. Grevillea species showed highly variable breeding systems: G. linearifolia was self-incompatible (SI = 0.003), G. sphacelata, G. mucronulata, and G. oleoides were partially self-compatible (SI = 0.07–0.28) and G. longifolia was self-compatible (SI = 0.61). Intrapopulation variability in the level of self-incompatibility was high in all species but G. linearifolia. The correlation between SI and FR: FL ratios was non-significant, indicating that compatibility has a minimal effect on fruit set in the Grevillea species studied, and that these data, together with other data on proteaceous species do not support trends observed in Sutherland’s survey. Low FR : FL ratios resulted from of a combination of pollen limitation, and high levels of flower and fruit predation.

Heat tolerance of rhizomes of several understory species

1983 ◽  
Vol 61 (2) ◽  
pp. 452-457 ◽  
Author(s):  
Marguerite A. Flinn ◽  
Joan K. Pringle
Keyword(s):  
Temperature Tolerance ◽  
Pteridium Aquilinum ◽  
Tolerance Index ◽  
Understory Species ◽  
Chamaedaphne Calyculata ◽  
Cornus Canadensis ◽  
Shoot Number ◽  
Different Temperatures ◽  
Maianthemum Canadense ◽  
Study Sites

Rhizomes of eight understory species: Gaultheria procumbens, Maianthemum canadense, Vaccinium angustifolium, Cornus canadensis, Pteridium aquilinum, Kalmia angustifolia, Chamaedaphne calyculata, and Rhododendron canadense were subjected to treatments of 45, 50, 55 and 60 °C for 5 min in a water bath. Selection of these species for study was based on differences in the depth of the rhizomes, in habitat, and in rhizome morphology. Samples were collected from study sites located near Halifax, in the Nova Scotia Acadian Forest region.Maximum shoot growth occurred at different temperatures for the various species: 45 °C for Cornus canadensis; 50 °C for Chamaedaphne calyculata, R. canadense, and V. angustifolium; 55 °C for G. procumbens and M. canadense. Death occurred at or below 60 °C for most species. For comparative purposes, a temperature tolerance index (TTI) was calculated for each species. The TTI indicated that R. canadense and V. angustifolium showed the greatest tolerance to higher temperatures and that K. angustifolia and P. aquilinum showed the least tolerance. Mean shoot number increased significantly following spring treatments for all species except for Cornus canadensis which showed greater increase following autumn treatments.

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