Besides the dignified name of Our Lord's Candle, the plant also has the colorful name of Quixote plant and the more mundane name of chaparral yucca. The plant is native to southwester California and adjacent Baja, with a disjunct population near the Grand Canyon. The preferred habitat is chaparral, but it can also be found in coastal sage scrub, grassland, and yellow pine forest.
Hesperoyucca whipplei was formerly known as Yucca whipplei, but detailed differences in the flower structure caused it to recently be moved to a new genus. The species is so variable that it is divided into four subspecies - percursa, caespitosa, intermedia, and parishii. The subspecies are each found in a specific location and that is the easiest way to identify them in their natural ranges. They also vary in if, how, and when the plant forms offsets and in size of the leaf rosette and the inflorescence. I am familiar with Hesperoyucca whipplei subsp. intermedia and H. whipplei subsp. parishii and will discuss here those two subspecies only.
H. whipplei subsp. intermedia is native to the Santa Monica Mountains and adjacent country of Los Angeles and Ventura Counties. It is a stemless plant with a rosette of many thin leaves, on the order of 2 to 2 1/2 feet long. The leaf color varies from green to blue-green. My observation has been that the green leaves tend to be more floppy in appearance than the blue-green leaves. The flower stalk is up to 10 feet tall, which is tall enough to stick up above the chaparral and a plant in bloom in quite noticeable. The parent rosette forms offsets at the time of blooming and the parent rosette dies as the seeds mature.
If you like H. whipplei subsp. intermedia, if you think it is impressive, then H. whipplei subsp. parishii will knock your socks off. The published literature says that the flower stalk is up to 13 ft tall, but I think they get taller. There can be upwards of 600 flowers on one inflorescence. The stalk is bigger around than my arm. The leaf rosette of H. whipplei subsp. parishii is stemless, but unlike the laid-back Malibu attitude of H. whipplei subsp. intermedia, the H. whipplei subsp. parishii bristles at attention in a beautiful sphere. Leaves are about 3 feet long and the plant is blue-green. Subspecies intermedia is found in the San Gabriel and San Bernardino Mountains. The plant does not form offsets and it dies after blooming.
Both subspecies bloom in late May and June. It is reported the flower stalk can grow up to 14 inches a day. Plants take from around 10 year to 50 years to reach maturity.
The pollination of H. whipplei is a textbook case of symbiosis. The plant is pollinated by a yucca moth and apparently nothing else. When the moth is pollinating, it is also laying eggs on the flower ovary. The larvae feed off of the developing seeds, but not all of the seeds. Thus both species survive with the help of the other and neither could survive without the other.
H. whipplei can easily be grown from seed. Just start them in pots like you would tomatoes or marigolds or other conventional plants. I use regular potting soil, but if your climate is humid, it might be better to use a cactus soil mix. Plants transplanted into the ground should be planted in well-drained soil and get at least a half day of direct sun. In my yard, the soil is clay, which is not really the preferred soil for H. whipplei, but the climate is dry and they are planted on a slope. We did lose one plant in an El Nino year when we got 40 inches of rain over a couple of months. Plants beyond the seedling stage should get minimal summer water. Plants should be planted well away from foot traffic and play areas. Each leaf has a needle-sharp tip. The species is reported to be hardy in zone 8 and warmer.
All photos on the left are of ssp. intermedia and all photos on the right are of ssp. parishii. Photos are property of Kelli Kallenborn.
(Editor's Note: This article originally ran February 2, 2009.Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your questions.)