San Francisco has a beautiful flower collection at the Conservatory of Flowers in Golden Gate Park. If you love Orchids this is the place to go because they have many different types of Orchids planted all throughout the building.
The conservatory is divided into five sections which are the Lowland Tropics, Highland Tropics, Special Exhibit, Aquatic Plants and Potted Plants.
My favorite section of the Conservatory was the Special Exhibit section because at the time of my visit they featured Butterflies which would fly all around you and if you are still enough you might also have the chance of one landing on you. I had several chances to hold different butterflies because they kept on landing on me. My other favorite section was the Aquatic Plants because they had so many unusual looking species of plants like the Carnivorous Plant and they also had a large pond in the middle with several Amazon Waterlilies. I learned that the Amazon Waterlily is the largest waterlily and it blooms only 3 nights. The first time it blooms it is white the second night it is pink and the third night it turns a purplish red.
I highly recommend visiting the Conservatory of Flowers if you are traveling to San Francisco or if you live in the Bay area. Plus it is not expensive to get in.