Pentapterygium.

I am not familiar with Pentapterygium so I looked it up and here is what I found:

AGAPETES (Pentapterygium) serpens. Native to Himalayan region as are many rhododendrons and azaleas. An unusual low shrub related to the huckleberries (Vaccinium). It has meandering branches neatly lined with narrow, glossy 3/4" leaves which are heavily tinged with red in new growth. Older branches carry many pendant dark red, tubular flowers in summer, with an occasional sprinkling at other times. A fine subject for shady plantings with ferns, and for large hanging baskets. ÂLudgvan Cross is a hybrid between this species and A. rugosum. It is of distinctly more upright habit, growing at least 4' tall. It has larger, broader leaves and small clusters of 1½" flowers checkered with maroon on a cream-white background. Light to medium shade; acid, well drained soil, moderate watering. Hardy to 15-20oF.

I have never seen it, I guess because it is way too tender for PA. However it is an Ericacioius (acid loving) plant, a distant relative of azaleas. It is said to attract hummingbirds also. It is grown by Suncrest Nurseries which according to their website, is a big supplier to CA retail nurseries.

Here is a link that might be useful: Sources of Agapetes.

Rhodyman and bboy, thank you both. I've ordered the plant.
Alice

I think the best hanging plants for Rhododendron as Vireya
and it can be blooming all the year round and some had nice scent.
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and you can see it so wonderful dreamy flower
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Thank you, charlotmteng, but I've already bought the agapetes.
Alice