A recent vacation to San Diego offered the opportunity to see “in person” plants I’ve only seen and admired in pictures. This was a pleasure on many levels, not the least of which was a huge variety of the countless hues of green.
I spent most of my short vacation in Balboa Park, exploring the many gardens and plantings throughout its 1,200 acres. As I walked north on 6th Avenue headed towards the Cabrillo Bridge entrance, I was greeted by the opened-arms, exuberant look of a group of tall Hoop Pines (Araucaria cunninghamia). Cousins of the Monkey Puzzle tree (sometimes seen in the Pacific Northwest), Hoop Pines have similar dark green, sparse foliage but are less conical and have a wider canopy than Monkey Puzzle trees. Farther in the park, tall palms* and Loquat (Eriobotrya japonica) dot the landscape, bringing a tropical, exotic feel to the many paths inviting visitors to explore. Palms are attractive, and I appreciated seeing them close-up, but after a while they all begin to look alike. And I didn’t find the one palm I was searching for – the Thai Mountain Fishtail Palm (Caryota gigas). (This is a palm worth traveling to the ends of the earth for, which someday I will do.)
In the meantime, however, I changed course and headed to the Desert Garden – my initial destination. I have seen pictures of this garden, and expected a wide variety of plants new to me, but I was awe-struck by what I found. Here, looming huge, contorted, and distinctive, were hundreds of cacti in shapes and sizes that I didn’t know plants could achieve. From the Spiked Cabbage Tree (Cussonia spicata) to Candelabra Tree (Euphorbia candelabrum), from the charming Pig’s Ear (Cotyledon orbiculata) and enormous Paddle Plant (Kalanchoe thyrsiflora) to the many bright Golden Barrel Cactus (Echinocactus grusonii), from the busy Chandelier Plant (Kalanchoe tubiflora) to the high-spirited chaos of an Indian-fig Prickly Pear (Opuntia ficus-indica), every available space was filled with the evidence of how plants have adapted to environments that are as harsh and miserly as any on earth. Also among this outstanding collection were many Aloes and Agaves.
As I rounded a corner, not entirely watching ahead of me, I came face to face with a drooping Euphorbia ingens in all its tall, weeping glory. I don’t know if this wondrous plant has a common name, but I would name it something grand like Tears of God or Many Arms of God; maybe God’s Broken Heart.
Impressed as I was with the multitude of shapes and sizes that these spectacular cacti have developed, it was the differences in the color green between each genus and species that most amazed me. Subtle shades of green-brown, tan-green, bluish-green, light and dark green on the same plant, green-purple, red-green – what accounts for this variety? A plant’s environment – heat, sun, shade, water, nutrients, insects, disease – acts upon the plant in ways we do not entirely understand. We do know where cacti store water (in the stems) and why most cacti stems are round (more efficient water storage capacity). We do know that the stem is where photosynthetic activity occurs, and we know that the spines of a cactus are modified leaves. We know, also, that water stored in the stem is converted into a more viscous solution which inhibits evaporation. This solution also protects the plant in freezing weather. We know quite a lot about the reasons behind cacti shapes. But the colors! Some cacti have a wax-like covering over their skin (a cuticle covering the epidermis) that reflects light, but there must be other reasons for the wide variety of colors. We know that some environmental influences produce an immediate response in a plant; some influences may show years later – especially in long-lived plants. I suspect that is part of what accounts for such a variety in the family of cactus.
The many different ‘colors’ within a green plant are one of countless tangible demonstrations of life and its resolute ability to survive.
*Just a few of the many palms I saw in the park:
Bismarckia nobilis, Bismarck Palm
Butia capitata, Jelly Palm
Phoenix canariensis, Canary Island Date Palm
Syagrus romanzoffiana, Queen Palm
Washingtonia robusta, Mexican fan Palm
To see pictures of Balboa Park’s Desert Garden, go to Balboapark.org/Desert Garden. You will be amazed!