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  • What is the most common symbiotic relationship in the plant kingdom, involving over 80% of plant species?

    Posted on December 2nd, 2010 admin No comments

    Tweet your answer to  I’ll post the answer tomorrow afternoon EST.

  • Why are peanut allergies suddenly becoming more common in North America than elsewhere in the world?

    Posted on December 1st, 2010 admin No comments

    Nobody gave the answer I was looking for.  The answer from @jchaager is probably at least partly correct:  “Parents are raising their kids in a bubble and preventing early exposure to allergens that would build up their immunity.”

    The “overprotective parents” hypothesis (or “hygiene hypothesis”) of increase of allergies is probably at least partly true, but doesn’t lend itself to experimental verification.  What parent would agree to raise their child in “dirty” conditions for experimental purposes?  Nevertheless, there is some anecdotal support of the idea.  On the other hand, there is also experimental support of the idea that exposing a child to an allergen too early may trigger an allergy rather than boost their tolerance.

    Anyway, there is a biochemical and cultural cause that is hypothesized as a reason for increased peanut allergies in North America.  In North America, most peanuts are roasted, rather than boiled.  Boiling, as done in most of the rest of the world, neutralizes some allergens in peanuts.

    One of the main allergens in peanuts is “Ara h2,” which inhibits protein digestion.  Roasting peanuts makes this protein more effective at blocking protein digestion.  Thus, once a person with peanut sensitivity ingests Ara h2, other undigested proteins in the peanuts cause further allergic reactions.  Boiled or raw peanuts have less effective Ara h2, so are far less likely to trigger allergic reactions than roasted peanuts.

    More specifically, Ara h2 inhibits the action of the enzyme trypsin in the digestive system, which normally breaks down the peptide chains in proteins, liberating the component amino acids.  These undigested peptides are thought to be a contributor to the abdominal symptoms of peanut allergies.

    More about peanut allergies:

  • What human disease was caused by the rapid spread of corn throughout the world in 18th century?

    Posted on November 24th, 2010 admin No comments

    First correct answer was from @mlv: Pellagra is a niacin deficiency disease caused by rapid spread of corn-based diet.

    Pellagra, a niacin deficiency, was caused by the rapid spread of a corn-based diet and by improper preparation of the corn.  Traditional preparation of corn included soaking in alkali.  This released the niacin and prevented pellagra.  When Europeans spread corn from the Americas to other parts of the world, and it became a staple of many impoverished populations, they failed to spread the cultural traditions that made the corn a properly nutritious staple food.

    Note that pellagra is not caused by corn in the diet, but is not prevented by a nearly exclusive diet of corn.  It’s a matter of balance.  Anyone can certainly eat corn without fear of niacin deficiency, but if their diet includes no other significant source of niacin, they may be in trouble.

    Modern strains of corn have been selected to make niacin more accesible to digestion without alkali processing.

    Pellagra is still a problem in some refugee populations where corn is provided as an unfamiliar new staple food.

    More about pellagra:

  • What plant-based component of traditional North American Thanksgiving feast is named for a bird?

    Posted on November 22nd, 2010 admin No comments

    First correct answer was from @ilrokery:  The cranberry is a traditional Thanksgiving food that was named for a bird (originally “crane berry”).

    The cranberry was so named for the resemblance of its flowers to a crane’s courtship display.  The cranberry’s petals curve far backward, exposing the anthers and stigma, like the outstretched neck and backard-pointing wings of a courting crane.

    The cranberry is native throughout high latitudes of the Norhtern Hemisphere, but was first used as food in the Americas.  As a food introduced to the English by the Indians, cranberries (usually as sauce) became part of the traditional Thanksgiving Day feast.  After the Indians introduced them to cranberries, Europeans began harvesting them in the Old World as well.

    More about cranberries:

  • Term for perennial plants which produce above-ground parts only in spring, then die back to underground parts.

    Posted on November 12th, 2010 admin No comments

    No correct answers to this one: Perennial plants that produce above-ground parts only in spring are called “spring ephemerals.”

    The strategy of spring ephemerals is to leaf and flower in early spring, when trees and other taller (mostly woody) plants have no leaves.  They use the energy they stored last season to produce their leaves and flowers very early in the season, then store energy underground for next season.  Spring ephemerals include many woodland flowers which can be seen before trees shade them, then disappear in summer.

    Spring ephemerals are different from annual or “weedy” ephemerals in that they have perennial bulbs, roots, or rhizomes.  The “weedy” ephemerals survive their non-growing seasons in the form of seeds, while spring ephemerals survive underground.

    Trillium species are often cited as examples of spring ephemerals, but many of them do persist above ground through summer and fall.  I have observed Trillium erectum, T. grandiflorum, and T. undulatum in leaf and in fruit well into fall.

    More about spring ephemerals:

  • What chemical characteristic do the flowers of forsythia have in common with mammals?

    Posted on November 3rd, 2010 admin No comments

    First correct answer was from @rozberk:  Forsythia is one of very few plants which produce lactose (milk sugar) in their nectar.

    The most common sugars in nectar are more typical “plant” sugars, like sucrose and fructose, or even glucose.  Forsythia produces lactose, the main sugar in the milk of mammals.  Few plants produce lactose.

    Forsythia is a genus of striking shrubs that produce a profusion of bright yellow flowers before the leaves in early spring.  (Their common name is the same as their genus name, forsythia.)  Forsythia is native to East Asia, and one species, F. europaea, is native to the Balkans.  Many species, cultivars, and hybrids are commonly cultivated throughout the world, and naturalized in many places.

    More about forsythia and nectar: and

  • How do larvae of monarch and related butterflies avoid getting their jaws gummed up by the sap of milkweed plants?

    Posted on November 2nd, 2010 admin No comments

    No correct answers to this one.  Monarch butterfly caterpillars (and relatives) cut the veins of leaves before feeding to avoid gummy sap.

    When very small, the caterpillars simply feed on the surface of the leaf, then move to a different spot when the sap begins to flow.  Sometimes they do get their jaws stuck in the latex-rich sap, and caterpillars often starve as a result.

    When they grow large enough, the caterpillars cut a vein near the base of the leaf, then eat the part that has been cut off from sap.  All the latex that the plant exudes to try to repel the attack leaks out through the cut vein, and the caterpillar can feed in safety.  This technique allows monarch and related caterpillars to feed on milkweed leaves despite their sticky, gummy sap.

    Besides coping with sap that would glue their jaws shut, monarch caterpillars must also tolerate toxins within milkweed leaves.  They do this successfully, and even incorporate the toxins into their own tissue, rendering the caterpillar and the butterfly that develops from it toxic to predators.

    More about monarch butterfly caterpillars:

  • What is the botanical difference between a pumpkin and a squash?

    Posted on October 25th, 2010 admin No comments

    First sort-of correct answer was from @jchaager:   “Pumpkin are round, squash are weird shaped.”

    That answer doesn’t sound very scientific.  That’s okay, as there really is no absolute scientific difference between a squash and a pumpkin.

    Squash, gourds, and pumpkins are all members of the family Cucurbitaceae.  The term “gourd” can apply to any plant of this family, but it usually refers to the bottle gourd (Lagenaria siceraria).

    The difference between a “squash” and a “pumpkin” is even more vague than that between these fruits and a “gourd.”  A plant of a given species may be either a squash or a pumpkin.  Those squash that are called pumpkins are particular varieties selected for “pumpkin-like” characteristics, but varieties of the same species may be called squash.  Generally, a pumpkin is orange, large, and has a more woody and angular stem than a squash.  A squash stem is softer and straighter.  Generally.

    Pumpkins are squashes of the genus Cucurbita (especially C. pepo, C. mixta, C. maxima, and C. moschata).  Some varieties of C. pepo are called pumpkins, but others are called zucchini, and still others summer or winter squash.  They are all the same species, just different “cultivars” or varieties.  Some varieties of C. maxima are called buttercup squash, but others are among the largest pumpkins on record, reaching well over half a ton.

    Certain pumpkin farmers whom I know personally always call their crop “squash,” and scoff at the “tourists” who call them “pumpkins.”

    More about pumpkins: and

  • (For those in Temperate Zones.) Did you ever see a sweet potato flower? Why not?

    Posted on October 7th, 2010 admin No comments

    No answers to this one.  (People just aren’t interested in plants.)  Sweet potatoes don’t bloom outside of the tropics because their reproductive cycle is governed by the length of daylight.  They never flower when the daylight is more than 11 hours long.  And of course, when the days are shorter, it’s too cold for these tropical plants to bloom

    When they do flower, sweet potatoes produce a flower very much like a morning glory, to which they are closely related.

    Outside the tropics, sweet potatoes are propagated only by cuttings of stems or roots, not by seeds.

    With artificial control of temperature and duration of light, sweet potatoes can be made to blossom in any climate.   But growers usually don’t bother, because it is so easy to propagate them with cuttings.  They are made to blossom in hothouses only for purposes of cross-breeding several strains to produce new strains with desirable characteristics.

    More about sweet potatoes:

  • On my blog, I categorized a recent question involving lichens as “plants.” Is this correct?

    Posted on October 1st, 2010 admin No comments

    (This one is mostly food for thought, though there is an element of “correct” vs. “incorrect” about it.)

    Among the many correct answers to Friday’s question were those from @little_mavis and @KessCat.  (More on that below.)  Notable in his own way, @mlv says “Yes” and @mlv says “No.”

    This question is partly about modern taxonomy and partly about the nature of a lichen. 

    First, a little taxonomy background.  Many people still think of living things as either animals or plants, but scientists do not.  As discussed in one of these trivia questions some time ago,  there are now 5 or 6 kingdoms of living things, depending on whom you ask.  Some things formerly classified as “plants” are now considered to be members of separate kingdoms, including the kingdom, Fungi.

    So, if a lichen is a fungus, it’s not a plant.

    This brings us to the second part of the question, regarding the nature of a lichen.  A lichen is not a fungus.  It is not even an organism. It is a community of a fungus and a photosynthesizing organism.  The photosynthsizing member of a lichen is usually an alga (Kingdom Plantae), but sometimes a cyanobacterium (Kingdom Bacteria).  The symbiotic community of a lichen is still sometimes given a binomial scientific name (usually the name of the fungus component), but it is really two things and can not be classified under a single genus and species.  It can’t even be classified into a single kingdom.

    The members of most lichens usually do not live separately in nature, but some can live separately.  In a few cases, a single species of fungus can live either on its own, as a lichen in symbiosis with an alga, or as a lichen in symbiosis with a cyanobacterium.  In all cases where the components of a lichen can live independently, the lichen lives in a broader range of habitats than either member can live alone.

    A lichen is not a plant, though most lichens have a member which is a plant.

    So, my categorization of the lichen question under “plants” was mostly incorrect, but colloquially correct as far as most of us would think.  Most of us, upon seeing a lichen, think “plant.”

    Incorrect as this is, I’m not going to change it.  No need to have a separate category on the blog just for lichens.

    Here are some of the answers I received, showing that some of my followers gave this question some thought, even if they didn’t know.  And thinking about it is the whole point.

    @little_mavis:  I’m fairly sure they aren’t plants but I’m not sure what they are. Seem more like a fungus.

    @KessCat:  Yes and no. It’s often called a simple plant, but lichen is actually the result of an algae and fungus growing together.  Therefore, it’s a combination of both the “monera” kingdom and “fungi” kingdom. Neither completely one or the other.  It’s pretty cool actually.

    NOTE:  “Monera,” which @KessCat mentioned, is a kingdom now generally considered obsolete, which was once used for all prokaryotes, now usually divided into two kingdoms, Bacteria and Archaea.  Cyanobacteria, which are a component of some lichens, would have been classified in Kingdom Monera.  There is still some debate on the classification of algae, but most experts now consider algae to be members of Kingdom Plantae.