Hot answers tagged botany
12
While poison affects not every organism equally, plants did develop some poisons to avoid being eaten. However, if you look at the great multitude of so-called secondary metabolites, most of them are poisonous to either viruses, bacteria, fungi or other microorganisms, or insects, or even other plants. Plant evolution just hasn't had time to adapt to humans.
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11
Yeast are neither plants nor animals; they are fungi. The old classification where things were lumped into only two buckets - plants or animals - has long since broken down. In fact, even things you might think of as plants, like algae or most seaweed are no longer classified as plants. Under the old system, plants and animals were considered kingdoms, and ...
10
There are some other good answers which provide part of the picture, but I think there is a fundamental organising principle which has been missed. Konrad has touched on it in his answer.
The reason trees, and most plants, tend to grow equally in all directions is that they have iteratively generated branching and radial symmetry which is controlled in a ...
10
It's probably Arbutus unedo, strawberry tree. Native to Mediterranean region and some part of western Ireland.
Edit: I've just spot that you found it in California, so it's probably one of north american Arbutus species, eg. Arbutus menziesii.
8
Photosynthetic pigments are the chemicals which take part in photosynthesis, in particular they are they ones which absorb photons and fluoresce (emit photons of a different wavelength) or emit electrons. Pigments are molecules, and chlorophyll is a key example. These pigments are required for photosynthesis to take place, as they generate the electrons ...
7
I've been doing some reading, and have come up with the following interesting information.
Telomeres
During cell division the DNA is replicated, but the mechanism is imperfect and in each round of cell division a small section is lost from the end of each chromosome. To compensate and protect the genetic information there are caps – regions of excess ...
7
In flowering plants (the angiosperms) there are several developmental transitions in the life of the plant. I won't list the plants, because the list includes pretty much all of them (although the magnitude in the change of developmental pace differs widely between taxa and environments).
First there is seed germination, which is controlled hormonally. ...
6
The general mathematical relationship requires an allometric equation. There are not as many for seedlings as there are for mature trees (but see the answer by @Richard-smith for a specific example). But lets start with a basic assumption that the emerging seedling will be a very tall cone (tall = high h to r ratio).
The volume of a cone is:
$V = ...
6
Yes, plants of all sizes can have cancerous growths.
Agrobacterium tumifaciens, the causative agent of crown gall disease, produces what is called a tumor. See this link for detailed information on these growths. Alternatively, use a plant physiology textbook to look up the above terms. (Here, is where a textbook is better than a single abstract in PubMed.)
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5
I can only answer for plants. The short answer is no, there is no central source of information of that kind.
You are basically asking about the sub-classifications economic botany and ethnobotany, which cover the economy and human uses of plants respectively. Neither field is particularly fast-paced, so you could simply keep up to date with the latest ...
5
In general, plant cells only undergo differentiation at special regions in the plant known as meristems. Two of the primary types of meristem are the root apical meristem (at the tips of roots) and the shoot apical meristem (at shoot tips)^. Within the shoot apical meristem the plant cells divide and begin to differentiate into different cell types (such as ...
5
It looks indeed like a Spirogyra, or at least a member of the Zygnematales.
And yes, the green things are the chloroplasts (or one long chloroplast?), and they are arranged in spiral.
The "empty" space in the middle is likely the nucleus, and the darker circles within the chloroplast(s) could be the starch accumulated at the periphery of pyrenoids.
5
In high school, we did an experiment that showed this.
Basically, if you take a glass of water, and let it sit out, perhaps in front of an open window, it will eventually lose water due to evaporation. It may take a few days/weeks to really see a large difference, but the level will go down. But, if you take a few flexible straws, put them in so the bendy ...
4
As with the massive variety of compounds that serve to protect plants against insect and animals, resulting in a wide range of poisons, antibiotics and other natural insecticides, allelopathic compounds are highly varied with different methods of action: some merely prevent germination while others are effectively herbicides.
One example is Alliolaria ...
4
To answer your specific questions...
Does nutrient availability limit emergence depth?
Yes, the size of the nutrient store in the seed does impose a theoretical limit on the maximum depth at which seed germination and emergence can take place.
What is the best depth for a given species?
The specific depth which gives best germination for any given species ...
3
A classic example is juglone from Black Walnut tree roots. This review from 1973 discusses juglone and allelopathy, inhibiting growth of other trees. This 1961 paper describes juglone's effects as able to sedate or at depress movement of Daphnia magna, leopard frogs, perch, catfish, goldfish, mice, rats and rabbits. That led to work testing juglone on cancer ...
2
One significant point not considered in previous answers is the reproductive rate and environmental variability. Larger animals have longer times between generations and generally reproduce less rapidly. In a less stable environment, more rapid reproduction allows more rapidly adapting population to the availability of resources, providing a larger ...
2
They absorb minerals through pores in the leaves known as stomata, this is some what similar to the way a medicine patch is absorbed on human skin except for the fact that the human skin has sweat pores instead of stomata.
Here is a animation of them opening and closing on a tomato plant provided by Wikipedia:
sources:
A nice review by Wocjik (2004) ...
2
Plants are not a strong suit for me, but in general the answer is yes. What I know mostly comes from animal tissue, so someone may have a better answer than I...
Botanists have been cloning plants from cuttings for thousands of years. More recently, propagation from cell lines around for much longer than for animals. Entire plants can often be grown from ...
2
Based on what I've been able to locate on the USDA website:
Refrigeration & Food Safety
It would be better to take the foods out of the bags and put them in the crisper if you're using the crisper solely for vegetables:
Some refrigerators have special features such as adjustable shelves, door bins, crispers, and meat/cheese drawers. These features ...
2
Recently, samples from different parts of cottonwood trees have been sequenced (Nature News). The conclusion:
“The variation within a tree is as great as the variation across unrelated trees,” says Ken Paige, an evolutionary biologist at the University of Illinois at Urbana-Champaign, who led the team that made the discovery.
This doesn't say anything ...
2
I think you may have covered the answer in your question... but here's my take;
The 'mowing' occurs at a distinct time-point and is highly destructive and uniform, so the selection pressure is very high and only highly competitive species that are fast to grow and reproduce will be successful.
As you point out, animals will defecate and naturally fertilize ...
2
It sounds like you are interested in beta diversity which is the change in taxa composition (i.e., alpha diversity) between plots. There are a number of approaches to calculating beta diversity and the correct choice generally depends on the question(s) you are trying to answer. The most common approaches are very well described in this paper:
Anderson, ...
2
This article analyses the exchange of DNA during the process of grafting
Exchange of Genetic Material Between Cells in Plant Tissue Grafts - Stegemann and Bock, Science 2009
Quoting from the article:
Although the grafted tissues fuse and establish vascular connections,
the stock (the lower part of the graft) and scion (the upper part,
usually ...
1
The phenomenon you are asking about is allelopathy.
Remarkably, it has its own journal - Allelopathy Journal (ISSN:
0971-4693) published since 2009 and currently at volume 30, issue 1.
Here are the titles of the papers from the most recent issue:
In-vitro assessment of allelopathic effects of wheat on potato.
Allelopathic effects of sunflower on ...
1
As @MCM says, the capsaicin molecule isn't intrinsically damaging - its effect upon us is mediated through the TRPV1 (Transient Receptor Potential Vanilloid 1) receptor in the membranes of cells whose function is to sense noxious stimuli such as heat. The binding of capsaicin to this protein causes transmembrane movement of Ca2+ ions which depolarises the ...
1
Here is a good USDA link:
http://www.usna.usda.gov/PhotoGallery/FallFoliage/ScienceFallColor.html
It would appear that the shortening days are a main trigger, and there are other factors. I did a basic search using Google for "what triggers leaf fall in deciduous trees?", since I always thought temperature and changing seasons were major triggers and ...
1
If you ask Dr. Duke's phytochemical database, by far the most solanine is found in green potatoe fruits (their skin), with much less in leaves and tissues. Similar values are seen in green tomatoes, with dozens of mg per 100g fruit. There is no value for Solanum dulcamara (doesn't mean there is nothing in it) but it appears to have small quantities of ...
1
Other possible reasons except your and Luke's:
Different agriculture techniques. I could imagine machine-mowed grassland could be processed by different chemicals (fertilizers, insecticides). I could imagine machine-mowed grassland could be sown with different grass that grows faster but dies when trampled with hoofs.
Most agriculture machinery works on ...
1
You might want to look at Koleff's paper (open access @ JAE http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2656.2003.00710.x/abstract).
Given that you have quantitative data, you should look at the difference between presence/absence and quantitative measures. A Bry-Curtis measure or something to that effect would be way better than a Sorensen or ...
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