Low Chill Lilacs

The lilacs are blooming in the local park where this nursery was once located. No labels exist on the bushes. How do we know what they are?

Checking in some old catalogs, I found this:

"Our efforts in behalf of Lilacs may be attributed to the splendid work of Mr. W.B. Clarke of San Jose, noted hybridizer of spring flowering shrubs and trees. It was he who developed the three excellent varieties pictured above."

I had thought that Descanso Garden was the place where low chill lilacs originated, but apparently it was in San Jose! And Descanso carried on.

• Lilacs for Warm Climates, Pacific Horticulture, Winter 1988
• Lilacs: A Gardener's Encyclopedia, Volume 35
• Oral History, Toichi Domoto "A Japanese-American nurseryman's life in California: floriculture and family, 1883-1992, Toichi Domoto", "W.B. Clarke, Lilacs"
• Inventory of the W.B. Clarke & Co. Nursery Records D-595
• List 22-H : season 1922-1923 / Clarke Nursery Co. ; W.B. Clarke.
• Mild Climate Lilacs, Sunset, "The first low-chill lilac, called 'Lavender Lady', was developed in Southern California 30 years ago by Walter Lammerts, a researcher and hybridizer with Rancho del Descanso" Oh, really? Check out Independent Press Telegram, below.
• San Mateo Times, Feb. 27, 1953, "Your Garden Column" article about W.B. Clarke.
• Independent Press Telegram May 18, 1958, "New Lilac for Western Gardens", "HERE IS THE background: In 1942 Dr. Lammerts was given the besf of the lilac seeds which the late Walter Clarke of San Jose had grown. Clarke had spent over 20 years selecting and re-selecting lilac strains that offered good blooming promise under mild winter conditions. Dr. Lammert's work, in turn, was just beginning. Back to UCLA, where he grew the seeds, then over to Descanso Gardens at La, Canada where they were matured and observed, and finally all but a few were discarded.
• Independent Journal, June 13, 1953, "One man responsible for many of our popular newer plants is W. B. Clarke of San Jose. He, for example, brought back to our gardens the much desired “yesterday, today and tomorrow" plant. This fragrant shrub out of Brazil had been in California gardens back in the 80s. In 1928 Clarke found it in an old Menlo Park garden. He propagated it, offered it to the trade again, and immediately amateurs everywhere, in Ukiah, to San Diego rushed it into the garden. "
• San Mateo Times December 12, 1952, "Your Garden Column".
• Nursery catalog from 1921-1922, with Lilacs
• Bio of W.B. Clarke in back of 1943 catalog with introduction of three new lilacs: Kate Sessions, Blue Hyacinth, an Alice Eastwood. Clarke worked at the CNC from 1905-1916. He worked for Luther Burbank for a short time there. Opened his nursery in San Jose. In business for 27 years as of 1943.

1943 Catalog 

Independent Press