The Triumph of Seeds (35 page)

40  
replacement for cane sugar:
Corn syrup comes directly from the starch found in maize seeds and can be purchased in the baking aisle of any grocery store. It is distinct from high fructose corn syrup, a variety processed with enzymes to intensify its sweetness. For an entertaining and informative look at the issues surrounding high fructose corn syrup, and the corn industry in general, I highly recommend the 2008 documentary
King Corn
.

41  
pressing the beans for butter:
Until the nineteenth century, people enjoyed chocolate primarily as a beverage, and its butter content was seen as an oily nuisance. The “Dutching” process (perfected by Holland’s van Houten family) removed butter from the nibs with the aim of making a better drinking chocolate. Only later did chocolatiers mix that extra fat back in with whole ground beans to invent the modern chocolate bar. For more on the fascinating history and science of chocolate, see Beckett 2008 and Coe and Coe 2007.

42  
acellular endosperm
:
Though ungainly on a product label, this term is very literally accurate. The coconut’s liquid endosperm develops
without
defined cells—it is just a bunch of nuclei splashing around in a puddle of cytoplasm! Other seed endosperms may experience a free nuclei stage early in their development, but only coconuts maintain this bizarre arrangement at maturity.

43  
perhaps thousands of miles:
In spite of the coconut’s remarkable dispersal ecology, its best trick for moving so far and wide has been to make itself useful to people. Virtually every native culture in the coastal tropics relies on coconuts in some way, and they’ve brought them along with them wherever they’ve traveled. Some evidence points to a Southeast Asian origin, but they were widespread from the South Pacific to Africa and South America long before botanists started asking questions.

44  
and then around the world:
While almond cultivation is widespread, it truly took root in California’s Central Valley, where several thousand orchards now produce over 80 percent of the world’s annual harvest. Nearly all California growers belong
to the Blue Diamond Cooperative, whose savvy marketing has helped almonds surpass grapes to become the state’s most valuable crop.

45  
product called “rape oil”:
Crop researchers at the University of Manitoba bred the current strain of commercial canola mustards to produce a more palatable, low-acid oil. The name comes from “Canadian oil, low acid.”

48  
fine musical instruments:
Until the advent of cheap plastics after World War II, sliced and polished tagua nuts made up as much as 20 percent of the button market in North America and Europe. They’ve recently been making a comeback in the fashion industry. See Acosta-Solis 1948 and Barfod 1989 for more on the history of this beautiful seed.

48  
“brain worm”:
In his 2008 book
Musicophilia
, Sacks notes an earlier and even more descriptive term used in Scotland for any maddeningly catchy tune: “the piper’s maggot.”

48  
PGPR . . . , from castor beans:
PGPR also contains glycerol, and the seed fat component sometimes comes from soybeans.

50  
eight times as effective as starch:
Though best known as a thickener, guar means something else entirely to firefighters, pipeline operators, or the designers of ship hulls and torpedoes. In minute quantities, it has the ability to create “slippery water,” a phenomenon that greatly reduces drag. One physicist described molecules of guar gum (and similar polymers) as double yo-yos, coiling and uncoiling in such a way that they prevent turbulent liquids from adhering to adjacent surfaces. The physics are still poorly understood, but in practice this effect speeds the movement of fluids through hoses and pipes. The US Navy has also studied it as a way to increase hull efficiency and reduce the noise of its ships, submarines, and torpedoes.

52  
“the Pennsylvanian” in their honor:
American geologists once considered the Pennsylvanian to be its own, full-fledged period, but it’s now considered a subdivision of the Carboniferous.

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HAT THE
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OSS
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64  
by the early Carboniferous:
Clear precursors to the seed habit appeared in the late Devonian, including primitive seed ferns with ovule-like structures and
Archaeopteris
, an ancient tree that was one of the first woody plants with male and female spores.

66  
precursors to eggs:
Technically, these large spores evolved into what botanists call
ovules
, reproductive structures that include eggs and several layers of surrounding tissue.

66  
step in the evolution of seeds:
While it’s easy to dismiss spike mosses and other modern spore plants as a minor part of the flora, they remain quite successful. Though the spore strategy is no longer dominant, it has persisted for hundreds of millions of years, and some lineages, particularly ferns, are more diverse now than ever.

67  
surface of leaves or cone scales:
Fruit-like tissues of various gymnosperms can be part of the seed itself (e.g., the red, berry-like aril of yew) or may derive from surrounding scales (e.g., the berry of a juniper). While they may carry out the same dispersal functions, these are not considered true fruits because they derive from different tissues.

68  
measured, incremental change:
See Friedman 2009.

69  
“the flowering plants”:
No seed book would be complete without a rant against this annoying and misleading phrase! Yes, angiosperms have flowers and fruits, but so do many gymnosperms, both extant and extinct. Just as their names imply, it is a seed trait—the presence or absence of a carpel—that defines these important groups.

69  
“. . . experiments in coevolution”:
Pollan 2001, 186.

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PORES

71  
in the spring of 1856:
Though he began his hybridization research in 1856, Mendel had devoted the previous two years to testing thirty-four local pea varieties, making sure they would breed true. In the end, he chose twenty-two of the most reliable strains for his experiments.

71  
free-swimming sperm:
Recent research shows that tiny mites and springtails may help transport moss sperm and facilitate fertilization (see Rosentiel et al. 2012). No one yet knows why they do it, but it’s a fascinating reminder that we still have a lot to learn about the spore-plant reproductive system.

71  
anything else from the spores themselves:
One intriguing exception to this statement comes from nardoo, a type of floating fern in Australia that features male and female spores like a spike moss. The larger, female spores come in little packets that can be ground, washed, and baked into cakes. Though they taste nasty
and are quite toxic unless properly prepared, nardoo cakes once served as an important desperation food for several Aboriginal tribes. Famed Australian explorer Robert O’Hara Burke and several of his companions reportedly died after eating improperly cooked nardoo (see Clarke 2007).

72  
some were wrinkled, and some smooth:
In total, Mendel tracked the fate of seven seed and plant characteristics: wrinkled versus smooth, seed color, seed-coat color, pod shape, pod color, flower position, and stem length. To keep things simple, I focused on the first and most famous trait, wrinkled and smooth seeds.

72  
what he actually thought:
With so little original material to work from, most biographical sketches of Mendel include a fair amount of speculation. Iltis (1924 in German; 1932 in English) remains the main reference. It’s an openly admiring portrait, but it benefits from the author’s interviews with people who actually knew the monk.

73  
unopened and unread:
While it makes a wonderful story to say that Mendel’s paper languished unread in Darwin’s library, such accounts are patently false. Meticulous searches of Darwin’s well-preserved collection have never uncovered a copy. Nor did he ever refer to Mendel’s work in his writing or correspondence. The two did come within twenty miles of one another when Mendel visited the Great London Exhibition in 1862, but Darwin was home at Down House at the time, and there is no reason to believe they ever met.

75  
dramatically through selective breeding:
While most crops and local varieties developed incrementally over long time periods, the sophistication and pace of plant breeding increased rapidly during the Enlightenment in the seventeenth and eighteenth centuries. See Kingsbury (2009) for a good discussion of this history.

75  
protection from cross-pollination:
The qualities that made it so good for wine depended on maintaining a double-recessive gene, and would disappear if the millet interbred with other varieties. This “glutinous” or “waxy” mutation occurs in many edible grasses, including rice, sorghum, corn, wheat, and barley. It is always a recessive trait, but the results are sometimes considered a delicacy (e.g., moshi, botan, and other sticky rice varieties).

76  
at random from each parent:
Mendel’s contributions to genetics are often summarized as the Law of Segregation (paired alleles, one from each parent) and the Law of Independent Assortment
(alleles passed down independently). He also gave us the terms
dominant
and
recessive
.

78  
bother with pollination at all:
The term
apomixis
describes several types of asexual reproduction in plants. For hawkweeds, dandelions, and many other members of the aster family, incomplete meiosis in the egg-forming process creates viable seeds that are essentially clones of the mother plant. Apomictic species may lose the advantages of regular genetic mixing, but they gain the ability to reproduce at will without reliance on pollinators (and most, if not all, retain the ability to reproduce normally in a pinch). If a species is well adapted, this strategy can be quite successful, as anyone with a lawn full of dandelions can attest to.

78  
“. . . changed the subject”:
C. W. Eichling, as quoted in Dodson 1955.

79  
“. . . evolution of
particular
forms”:
Bateson 1899. William Bateson, an eminent British botanist, made this statement in a talk to the Royal Horticultural Society. Quoted in more detail, his comments seem almost eerily prescient of Mendel’s pending rediscovery: “What we first require is to know what happens when a variety is crossed with its
nearest allies
. If the result is to have a scientific value, it is almost absolutely necessary that the offspring of such crossing should then be examined
statistically
.” Bateson went on to play a key role in championing Mendel’s ideas, and he coined the term “genetics.”

80  
three-to-one ratio:
The following year I planted my crosses and harvested a total of 1,218 peas. The ratio of smooth to wrinkled came in at 2.45 to 1, a close but not exact replication of Mendel’s famous result. The difference might have been due to my smaller sample size, or perhaps to pollen contamination from the pea varieties in Eliza’s nearby garden.

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ETHUSELAH

85  
endurance to the Jewish people:
For a fascinating examination of how the events at Masada transitioned from a historical footnote to a powerful story of heroism, see Ben-Yehuda 1995.

85  
set the building ablaze:
According to the Roman historian Josephus, the Sicarii left some portion of their provisions intact to show that they were well supplied until the end. This may explain
why some date seeds recovered from Masada are charred, while others are unburned.

85  
Jewish numismatics:
Until the finds at Masada, the provenance of certain coins minted during the Great Revolt had been considered “one of the most difficult problems of Jewish numismatics” (see Kadman 1957 and Yadin 1966).

86  
climate and settlement patterns:
After the Romans put down the Great Revolt and a subsequent uprising several decades later, the former kingdom of Judaea went into a steep decline. The export economy collapsed, whole towns were abandoned, and changing climate patterns made even small-scale date cultivation challenging. The once famous palm variety eventually winked out completely, as English clergyman and explorer Henry Baker Tristram wistfully observed on a visit in 1865: “The last palm has gone, and its graceful feathery crown waves no more over the plain, which once gave to Jericho its name of the City of Palm Trees” (Tristram 1865).