It’s been a real challenge, not to make this blog purely about botany. Plants are just so interesting! But, there’s a whole universe of interesting things out there, so I’m trying to maintain a strict one-plant-story-per-week limit. This week’s entry - the wonderful Rosaceae family. And yes, having a favorite plant family is a clear sign of botany geekitude. So, what, in my mind, sets the Rosaceae above the Cucurbitaceae? The Fagaceae? Even the all-important Poaceae? Well, we can start with the part where they taste delicious.
Rosaceae means “rose family”. That being said, this rose family can lay claim to the noble apple, the succulent peach,the versatile pear and the delightful cherry, among other plants. Most of the Rosaceae are in some way edible, even if rose hips and serviceberries aren’t necessarily abundant in the supermarket produce section.
Edible or not, the serviceberry is a very pretty tree.
Any family that contains both apples and roses is going to be large and diverse, even by the standards of plant families. What the Rosaceae all have in common is flower structure. Regardless of what kind of fruit the flower becomes, plants in this family are radially symmetrical, with five petals and five sepals (those green things behind the petals) arranged around a variable structure of stamens and overies (plant reproductive parts). After that, it gets a little more complicated. Most Rosaceae have simple leaves, but mountain ash have compound leaves. Quite a lot of the rose family has defensive structures (a.k.a. thorns), but only the desert-native blackbrush bears flowers on said defensive structures. Some members of the rose family are pollinated by insects, some by wind. And then there is the fruit.
Say it with me - yum!
Going by a scientific distinction, Rosaceae fruits can be divided into the drupes and the pseudocarps. Drupes are those fruits consisting of a single seed encased in a hard coating, surrounded by fleshy tissue called the mesocarp and ectocarp. When you eat a drupe, you eat the botanically defined fruit. Peaches and apricots are are drupes (also sometimes called stone fruits. Pseudocraps, on the other hand, contain multiple seeds surrounded by the fruit structure, which is then surrounded by fleshy tissue called the hypanthium. When you eat a pseudocarp, you are not actually eating the fruit, just the coating. Apples and rose hips are pseudocarps. However, for the purposes of use/eating, several other distinctions appear. Among drupes, the true stone fruits may be separated from the fruits of the Rubus genus, which consist of an agglomeration of small drupes (called drupelets). Raspberries are probably the most well known of this class. Pseduocarps may be separated into the pomes and the hips. In pomes, the hypanthium is fused with the outermost layer of the fruit (you can’t peel it away without somehow damaging the fruit), while in hips, the hypanthium is completely separate from the true fruit. And then there are pears, which are pomes, but contain special “stone cells” mixed in with the rest of the hypanthium. Hence the somewhat gritty texture that sometimes puts people off of pears. How almonds fit into this is somewhat beyond the scope of this posting. Let’s just say that almonds can be conceptualized as edible peach pits, and leave it at that.
Humans have had a long and fulfilling relationship with the Rosaceae family. Look at the apple. Apple cultivation stretches back 10,000 years. Through the development of the thousands of apple cultivars, humans learned many of the horticultural techniques (grafting, splicing, etc.) that continue to support orchards today (humans may have learned more from apples, depending on how literally you take Genesis). Classical literature from Greece, Rome and China sings the praise of apples, long before one Johnny Appleseed made his way along the American frontier. The history of peach cultivation only stretches back 4000 years, a relative newcomer when compared to the apple, and yet peaches have been diversified into thousands of cultivars, and spread far from their ancestral home in China. Rosaceae represent something like a quarter of all fruit production by weight, and are produced and consumed on every continent (except Antarctica. duh). And need I say anything about the sheer number of varieties of rose out there? From the Garden of Apple and the Golden Apple of Discord to the orchards of the Silk Road to love like a red, red rose to Sun Wukong and the peaches of immortality, human culture has been greatly enriched by the Rosaceae. So celebrate the Rosaceae in all their wonders. Chomp an apple, nibble a peach, contemplate a rose. We made them, and to some extent, they made us.
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