A reader called to marvel about two summer­time spectaculars in Hawaii gardens: the rainbow shower trees in gorgeous bloom around town and the night-blooming cereus along Wilder Avenue at Punahou School.

Rainbow shower trees are a made-in-Hawaii hybrid. They flower in warm rainbow shades for nine or 10 months of the year here. The parents of our "official street tree of Honolulu" are the golden shower from India and the pink and white shower tree from Indonesia.

Pink shower trees (Cassia javanica) bloom briefly in May (think Kaimuki and Kapahulu). The fragrant rainbow shower, which is usually sterile, is very drought-tolerant and blooms for months and months because it doesn’t waste energy producing lots of seed pods like the pink shower or the golden shower (Cassia fistula) from driest India. The parent varieties bloom for only a short spectacular time, then the flowers are pollinated and develop long brown seed pods full of stinky, sticky seeds. (We know because as kids we used them for sword fights and they made our hands stink. Also, I have cleaned the seed pods to plant seeds and this is not a fragrant enterprise either.)

One variety of rainbow shower is the Queen’s Hospital white or Queen’s white. It is actually pale yellow with some white flowers. If you walk before 7:30 a.m. at the Hale Koa Hotel, Kapiolani Park or other places where they grow, you will smell a delightful fragrance wafting through the air. It’s worth getting up early to get your blood pumping and your lungs working to inhale the subtle perfume.

Another nice variety is the Nii gold developed by R.S. Nii nursery in Hawaii Kai. It’s a bright yellow with orange buds.

Glenn Nii of the neighboring C. Nii Nursery (the nurseries were founded by brothers Charles and Shigeki) told me about one of his favorites, old gold, which has golden-yellow flowers with stalks that can reach 4 feet in length.

There are many other varieties and colors of rainbow shower. One of the originals is Wilhelmina Tenney, with its deep guava-sherbet color, mixed with yellow. The original tree grows in Foster Botanical Garden. It was transplanted from the Tenney garden in Makiki to make way for the Lunalilo freeway.

Their blooming is a sign of summer in Hawaii. Blooming usually starts around May and extends to November, but in recent years we have observed that you can find them in flower somewhere all year round.

Night-blooming cereus or panini o ka Punahou is actually a kind of cactus. The most famous planting of it in Hawaii is on the rock wall surrounding Punahou School in Makiki.

The plant, Hylocereus undatus, is from Mexico, where it is called pitahaya. It first landed in Hawaii around 1830 on the brig Ivanhoe, which was carrying plants collected in Mexico. Most of them died and were tossed overboard, and the nearly dead, dried-out cereus cutting looked like a goner, but First Officer Charles Brewer took care of it on the long voyage and planted it in Honolulu.

Its thorny stems send out aerial roots from the nodes or sections of stem. You can grow it from cuttings but watch out. It looks innocent at first but as it grows it can take over your rock wall, climb up slopes or trees, or even up your utility poles and lines.

(This happened at my parents’ home and they were without a phone for three weeks! I told my mom to keep it in a pot but she is too kindhearted and said, "It looked so cute and helpless in the pot.")

It is related to the dragon fruit that is becoming popular in Hawaii markets and gourmet flower arrangements.

Night-blooming cereus rarely fruits in Hawaii. In summer you can usually find a flower or two somewhere in the massive old planting. Some nights hundreds of them bloom. They open at dusk and if you pick one and put it in a vase on your dining room table you can watch it open. They have a nice faint fragrance and wilt the next morning.