Excerpts from Jim Conrad's
Naturalist Newsletter

from the November 20, 2011 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, México

A pretty thing to see nowadays is big, round, yellowing grapefruits in dark green trees beside shady village homes. You can see a typical cluster above. Grapefruits, like oranges and lemons, are citrus fruits, which means that they belong to the genus Citrus. You can see their typical citrus leaves with "winged petioles" causing the leaves look jointed at their bases -- orange and lemon leaves do the same -- below:

Grapefruit, CITRUS x PARADISI, leaves

A sliced-open grapefruit off the tree whose leaves are shown, with thicker rind and more seeds than I'm used to in grapefruits bought in the US is shown below:

Grapefruit, CITRUS x PARADISI, cut-open fruit

I'm wondering whether in that thick rind and numerous seeds there might be a story? For, the technical name for the Grapefruit tree is CITRUS x PARADISI, the "x" in the middle meaning that we're dealing with a hybrid. In other words, there's no "Wild Grapefruit" out in the wild from which today's grapefruit plants have been developed. The first grapefruits came into being in Barbados in the 1700s when an Orange plant, Citrus x sinensis, was crossed with a Pomelo, Citrus maxima, both species originally being from southern Asia, and Orange plants themselves being hybrids.

Pomelo (pom-EH-loh) fruits are very similar to grapefruits but much larger, their rinds are grossly thicker, and the wedge-shaped cells seen in cut-open fruits normally are more unevenly sized, causing the rind to be thicker above some cells than others. When I saw how thick-rinded, seedy and relatively dry-fleshed our grapefruit was, I wondered whether its parent tree might not have had more pomelo genes in it than most modern grapefruit trees do. Maybe grapefruit trees around homes in isolated little Maya villages derive from stock brought to the Yucatán by the Spanish during colonial times, before plant breeders produced cultivars with thinner rinds, fewer seeds and juicier flesh.

In fact, I'll bet that the Yucatán's little Maya villages are great places to find old strains of many cultivars, maybe strains going extinct out in the world as flashier ones take their place. And maybe sometimes the old strains have resistance to diseases or flavors or textures that newer ones don't.

While reviewing information on grapefruits I found that Wikipedia's grapefruit page not only has the usual praise of grapefruits and their juice as being especially nutritious and even medicinal, but also there's an interesting section on the grapefruit fruit's "drug interactions."

For, studies show that some compounds in grapefruit increase the effective potency of certain medicinal compounds, particularly those known as statins. This came to light when several deaths from overdoses occurred among people on medication who ate grapefruit -- grapefruit made their medicines too powerful. Grapefruit juice also can interfere with etoposide, a chemotherapy drug, some beta blocker drugs used to treat high blood pressure, and cyclosporine, taken by transplant patients to prevent rejection of their new organs. Grapefruit is powerful stuff! The Wikipedia page is at http://en.wikipedia.org/wiki/Grapefruit.

from the March 11, 2012 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, México

Wandering through the nearby little Maya town of Libre Union last Sunday we came upon the blossoms shown below:

Grapefruit, CITRUS x PARADISI, flowers with corollas fallen, ovaries enlarging

As indicated by the "winged petiole" of the leaf in the picture's upper right corner, this is obviously the flower of some kind of citrus species; neighbors sitting nearby on their rock fence told me the tree was a Grapefruit.

The flowers are past their prime, for their waxy-white corollas and stamens have fallen off, leaving in each blossom only a large, cuplike calyx, in the center of which arises a green, fast enlarging ovary, atop which arises a surprisingly thick style tipped with a large, blunt, brown stigma.

from the January 6, 2013 Newsletter issued from the valley of the Dry Frio River in northern Uvalde County, southwestern Texas, on the southern border of the Edwards Plateau, USA

Each day I spend a couple of hours digging a ditch for pipes to be placed in. Especially in this cool weather when the sun shines and a nice breeze blows, I look forward to the work, though I'm glad there's only two hours of it each day. The ground is rocky, sometimes solid rock. My favorite time is after working the first hour when I sit on the trench's bank and have a snack. In mid-snack the other day I saw the lovely thing you can see below:

Juice vesicles in pink grapefruit

I'd noticed the same thing many times before, but somehow that time the place and time were perfect for me to see more deeply, to luxuriate in the colors, textures, the attendant odors and tastes, and meanings. A good while I sat there just looking, marveling that such a commonplace thing on such an ordinary day could be so utterly astonishing.

The picture shows the face of a split-open red grapefruit. The shiny, elongate, baglike items are filled with grapefruit juice and are called juice vesicles.

So, thinking about fruit anatomy of such simple fruits as grapefruits, we can say that seeds are surrounded by masses of tissue known technically as pericarp. The pericarp itself is typically made up of three distinct layers: the exocarp, which is the outside layer or peel; the mesocarp, which is the middle layer or pith, and; the endocarp, which is the inner layer surrounding the seeds.

In grapefruits and other citrus fruits the exocarp forms the tough outer skin of the fruit, which bears oil glands and pigments.

The mesocarp is the white, pithy, somewhat bitter material immediately below the exocarp or peel, and is commonly removed before eating.

The endocarp is the part we eat, the part shown in the picture, formed of juice vesicles closely packed side by side.

In some fruits figuring out what is what can be tricky. For instance, most of the edible part of a peach and a considerable part of a tomato is mesocarp, which in citrus fruits is the white, pithy stuff right below the peel. Often I can't figure it out myself. I read reports from anatomists who have watched embryonic cells differentiate into the various parts.

Whatever things are called, the names or lack of names are hardly relevant when you're sitting on the edge of a trench you're digging through rock, the sun is shining, the air is cool and fresh, and a friendly breeze is passing through. What a pretty thing is the interior of a grapefruit. And what other everyday things do we underappreciate simply because the right time and place never arise for taking a good look?