No Evidence for Demographic Costs of Seed Production in the Pollen-Limited Perennial Herb Blandfordia grandiflora (Liliaceae)

1997 ◽  
Vol 158 (6) ◽  
pp. 785-793 ◽  
Author(s):  
Mike Ramsey
Keyword(s):  
Seed Production ◽  
Perennial Herb ◽  
Blandfordia Grandiflora

Flowering of Blandfordia grandiflora (Christmas bells) in response to fire frequency and temperature

2020 ◽  
Vol 68 (6) ◽  
pp. 449
Author(s):  
Stephen J. Griffith ◽  
Susan Rutherford
Keyword(s):  
Survival Rates ◽  
Fire Frequency ◽  
Perennial Herb ◽  
Fire Season ◽  
Frequency Effect ◽  
High Survival ◽  
Flowering Response ◽  
Flowering Season ◽  
Eastern Australia ◽  
Blandfordia Grandiflora

Blandfordia grandiflora (Blandfordiaceae) is a resprouting perennial herb in wet heathland of coastal and tableland habitats on mainland eastern Australia. It has attractive turbinate flowers of considerable horticultural value. Blandfordia grandiflora is reported to have an enhanced flowering response in the first post-fire flowering season, and management prescriptions advocate frequent fire as beneficial for the species. Nonetheless, the present study appears to be the first to document the flowering response and fate of individual plants exposed to a range of fire frequencies (3-, 6- and 9-year intervals) over an extended period. We also examined the flowering response in unburnt habitat. High survival rates (>95%) were observed for B. grandiflora plants in heathland that had remained unburnt for a minimum of 30 years. Flowering after experimental burns was found to peak in the second post-fire flowering season rather than the first, and there was no clear fire frequency effect. Maximum levels of flowering during the second post-fire season reached 38 to 56% of individuals, although in some years post-fire flowering during this peak season was as low as 23%. Comparatively few plants flowered during the second-year peak season after every fire, and ~34% of individuals in both the 6- and 9-year burn treatments failed to flower at any time. Inter-fire flowering was also observed, and in some instances this flowering was not significantly different to the level achieved during the peak post-fire flowering season. For example, ~9% of individuals flowered 5–7 times over a 12-year period despite being burnt on only four occasions. Flowering after vernalisation (winter-chilling) was observed in unburnt heathland, and the level of this response was not significantly different to peak post-fire flowering in some years. The findings are examined in the context of evolutionary and habitat processes within a climate change framework. Future studies should focus on the complex interactions between climate, fire and soil for not only B. grandiflora, but more importantly for the diverse assemblage of plant species in wet heathland.

The beneficial effect of ants on the reproductive success of Dyckia floribunda (Bromeliaceae), an extrafloral nectary plant

2003 ◽  
Vol 81 (1) ◽  
pp. 24-27 ◽  
Author(s):  
José L Vesprini ◽  
Leonardo Galetto ◽  
Gabriel Bernardello
Keyword(s):  
Seed Production ◽  
Reproductive Output ◽  
Fruit Set ◽  
Seed Set ◽  
Reproductive Organs ◽  
Extrafloral Nectaries ◽  
Perennial Herb ◽  
Seed Number ◽  
Total Seed ◽  
Mutualistic Association

Dyckia floribunda is a perennial herb from the Argentinian Chaco with extrafloral nectaries. Ants visited these nectaries while patrolling inflorescences and infructescences. We anticipated that ants attracted to extrafloral nectaries might protect the reproductive organs, increasing plant reproductive output. To evaluate the possibility of mutualism between D. floribunda and ant visitors, we determined whether ant-accessible plants showed a higher seed production than ant-excluded plants. Experimental fieldwork suggested a decrease in fruit set of ant-excluded plants compared with ant-accessible plants but the seed number per fruit was not affected by ant exclusion. Thus, total seed number per plant was highly reduced in treated spikes. Analyses of covariance confirmed these trends, indicating that total seed production per plant was strongly affected by ant exclusion. This study marks the first experimental report of this mutualistic association in Bromeliaceae.Key words: ant–plant interaction, Bromeliaceae, Chaco, Dyckia floribunda, fruit set, seed set, mutualism.

Selfed-seed production depending on individual size and flowering sequence in Iris gracilipes (Iridaceae)

2002 ◽  
Vol 80 (10) ◽  
pp. 1096-1102 ◽  
Author(s):  
Takashi Kimura ◽  
Hiroshi S Ishii ◽  
Satoki Sakai
Keyword(s):  
Seed Production ◽  
The Other ◽  
Perennial Herb ◽  
Pollination Experiments ◽  
Selfed Seed ◽  
Other Hand ◽  
Hand Pollination ◽  
Self Fertilization ◽  
Individual Size

To examine the influence of individual size and time of pollination on selfed and outcrossed seed production, we conducted hand-pollination experiments in 2000 and 2001 in the perennial herb Iris gracilipes A. Gray (Iridaceae). Small individuals produced outcrossed seeds to a greater extent than selfed seeds, whereas large individuals produced not only outcrossed seeds but also selfed seeds. On the other hand, when half of all flowering shoots of an individual were removed, both selfed and outcrossed seeds were produced independent of individual size. Flowers that opened earlier within the same flowering shoots were likely to produce outcrossed seeds, while those that opened later within the same flowering shoots produced relatively more selfed seeds than did the flowers which opened earlier. Thus, the ratio of the numbers of selfed to outcrossed seeds produced may differ between small and large individuals. These results suggest that plants regulate selfed- and outcrossed-seed production depending on their sizes and flowering sequence.Key words: self-fertilization, individual size, flowering sequence, Iris gracilipes.

Pilosella aurantiaca (orange hawkweed).

2021 ◽  
Author(s):  
Ghislaine Cortat ◽  
Gitta Grosskopf
Keyword(s):  
New Zealand ◽  
North America ◽  
Seed Production ◽  
Vegetative Growth ◽  
Perennial Herb ◽  
Native Range ◽  
Hieracium Pilosella ◽  
The Usa ◽  
Noxious Weed ◽  
Vegetation Loss

Abstract P. aurantiaca is a perennial herb which has spread rapidly in North America after its introduction as an ornamental and/or the contamination of pasture seeds from its native range in Europe. Although it is known to be a noxious weed elsewhere, it continues to be available as a garden ornamental and is therefore likely to spread further. It is an undesirable invader on account of its competitiveness, prolific seed production and vigorous vegetative growth leading to a drastic change in vegetation, loss in forage for stock, and loss of biodiversity. All Hieracium/Pilosella species are prohibited entry to Australia and New Zealand, and in the USA, P. aurantiaca is a declared weed in Colorado, Idaho, Minnesota and Washington.

Limitations on reproduction in alpine Ranunculus acris

1997 ◽  
Vol 75 (1) ◽  
pp. 137-144 ◽  
Author(s):  
Ørjan Totland
Keyword(s):  
Seed Production ◽  
Resource Availability ◽  
Seed Weight ◽  
Pollen Limitation ◽  
Resource Limitation ◽  
Limiting Factors ◽  
Perennial Herb ◽  
Plant Variation ◽  
Hand Pollination ◽  
Ranunculus Acris

This study examines experimentally the influence of limiting factors on seed to ovule ratio and seed weight in three alpine populations of the perennial herb Ranunculus acris L. at Finse, southwest Norway. To test for pollen and resource limitation, seed production of supplementally pollinated or completely defoliated plants was compared to that of untreated plants. In one population the experiment was repeated twice during the season. In mid-season, supplemental hand-pollination had no significant effect on seed to ovule ratio, but significantly increased the seed weight, whereas complete defoliation resulted in a significant decrease in seed to ovule ratio and a marginally significant decrease in seed weight. These results indicate that pollen limitation occurred on seed weight and resource limitation mainly on seed to ovule ratio. Seed production in late-flowering control and defoliated plants in one population was nearly completely absent, whereas supplemental pollination increased seed production substantially. Most seeds were produced at the lowest elevation, and frost damage on developing seeds was most pronounced at the highest elevation population, suggesting that severe weather conditions at the highest altitudes had a negative influence on reproductive processes. Significant positive relationships between seed number and seed weight were found, possibly reflecting a large among-plant variation in total resource availability. Key words: altitude gradient, climate, defoliation, pollen and resource availability, seasonal variation, seed size.

Sign in / Sign up

Export Citation Format

Share Document