What is this plant?

Question

We just moved in to a house and there are some plants in the back garden and just wondered what they are.

They are large plants, maybe 4 feet tall with green, long thin leaves. The flowers only come out about 9 pm and are yellow and smell faintly of lemon. They look dead during the day and just spring open suddenly at dusk.
No one seem to know what they are.

Ok people thank you all very much for your kind replies.
The plant has many "branches" and which seem to grow outwards as the year progresses like a foxglove, there could be as many as 50 blooms on one plant, and these blooms flower for maybe 7 nights, before falling off. I have seen moths in the flowers which are yellow and appear to have four petals. When fully open they are flatish, not trumpet shaped. I have seen these plants growing at the edge of the local fields too. I live in Yorkshire UK.

Very beautiful plant, hope it's not a weed!
As you can guess I am not an expert, this is the first garden I have owned which is not paved over, so I want to do my best for it.

As you are all so kind, I do not want to pick a best answer, therefore I leave it to all you plant experts to vote for the best one.

Answer 1

They sound like a variety of Day Lillies, I have orange ones which have long green "reed"-like leaves,, and as they begin to open they do indeed look dead. Day lillies because they open during daylight and close at night.... some are open all day, some open during the late afternoon or early evening. :-)

Answer 2

I'm with those who asked what growing zone you're in. That would help identify your mystery plant. Cereus, as one person suggested, is a columnar cactus, so far as I can see.
My guess is Angel Trumpet (Brugmansia aurea): Long spear shaped leaves, yellow trumpet shaped, downward facing, night scented flowers. The plants I've seen in our area get between 3 and 4 feet tall and are covered with bloom. I don't think they close during the day, but I could be wrong. I do know they're noted for haveing scent in the evening, but am not familiar enough to know if the scent is lemony.

Answer 3

I would have guessed four o'clocks, but these open in the late afternoon, not 9 pm at night. Also, they tend to be very fragrant, not "faintly of lemon" (although some find the fragrance to have a lemony character).

Otherwise, I would go with the evening primrose that was suggested above, although I have not come across any that are 4 feet tall.

Answer 4

are the flowers cup shaped? If so your plants could be Evening Primrose, the scented yellow flowers open at dusk and are pollinated by night flying insects, the flowers may last only a day or so, but are produced in abundance. It is a perennial plant and is OK in full sun or partial shade, in well-drained, sandy soils

Answer 5

I agree with Oaktalker. Check out his website link. Of course it IS NOT daylily. People-the poster said the flowers open AT NIGHT.

The state that you live in will help us to narrow down your options, as well as texture of the leaves (smooth, hairy, veiny, etc) and how the leaves are arranged on the stalk-opposite each other, palmate, clumped like grasses at the base of the flower stalk...What are the shape of the flowers? Trumpets? Multi-petaled? Are the stamen and pistol visible when open? More details.

Answer 6

Ok, this is a stretch, but could be a "night blooming cereus". I have one of these and they have large, fragrant, night blooming flowers, each which blooms but once. Flowers on my plant are light yellow to white. They open around 9pm and are at maximum bloom around midnight. By morning they fade and die. See the link cited below for pictures of what you plant might be.

Answer 7

There is a gladiola that has long thin leaves about 3 1/2 ft. tall creamy yellow blooms and blooms at night. (Gladiola tristis) It also has a scent. Try doing a google image search. Good luck and let me know what you find.

Answer 8

It could be an angels trumpet. The flowers only open early in the morning and at dusk.

Answer 9

Possibly night blooming jasmine, but it is hard to say because you don't mention what area of the country you are in. Different climates have different foliage.

Answer 10

Sounds like a bat pollinated plant such as an Agave.