Epiphyllum hookeri

Epiphyllum hookeri.

I must admit to finding the (sparse) information on this species to be very confusing
    and at times contradictory.
Among others sites http://www.worldfloraonline.org, www.plantsoftheworldonline.org,
    https://eol.org and the old Plant List give the accepted names and synonyms of species.
Epiphyllum hookeri is an accepted species with a number of synonyms including Epiphyllum strictum.

Part of the confusion is due to the fact that, even though Epiphyllum phyllanthus is an accepted species
    (with 16 synonyms), many subspecies and varieties under this name are actually synonyms
    for E. hookeri and its subspecies and varieties. For example:

  • E. phyllanthus subsp. guatemalense is a synonym of E. hookeri subsp. guatemalense.
  • E. phyllanthus subsp. hookeri is a synonym of E. hookeri.
  • E. phyllanthus var. hookeri is a synonym of E. hookeri.
  • E. phyllanthus var. columbiense is a synonym of E. hookeri subsp. columbiense.
  • E. phyllanthus var. pittieri is a synonym of Epiphyllum hookeri subsp. pittieri.

Epiphyllum hookeri is commonly known as Hooker’s Orchid cactus and E. phyllanthus as the Climbing cactus.
However some authors, inclucing the United States Department of Agriculture, has Epiphyllum
    phyllanthus var. hookeri (a synonym for E. hookeri) as the Climbing cactus.

Epiphyllum hookeri.

‘Hooker’s Orchid Cactus’ is an epiphyte with flattened, segmented stems.
The green stems, often with purple areas, can be up to 2 m long.
The midrib is prominent and the edges are scalloped.
The areoles have no spines.

Single flowers grow from the areoles along the stem edges.
They have no stalk but a short pericarpel and a long hypanthium.
There are short, reddish bracteoles on the hypanthium.

The nocturnal flowers are 15 to 20 cm across.
The outer tepals are a pale yellow-green and the inner ones white.
The many stamens insert into the top of the hypanthium.
They have white filaments and pale brownish anthers.
The anthers are basifixed and open via longitudinal slits.

The inferior ovary, about 1 cm long, is surrounded by receptacular tissue (the pericarpel).
The single reddish style has about 10 yellow stigmas.
There is a single locule in the ovary.
The numerous ovules, on long stalks, have parietal placentation.
The fruit are small ribbed, berries that ripen to a reddish-purple.

Epiphyllum hookeri subsp. guatemalense.
Epiphyllum guatemalense and E. phyllanthus subsp. guatemalense are synonyms.
The segmented stems can reach up to 7 m with adequate support.
They are flattened, fleshy with scalloped edges and have no spines.
The white, night-blooming flowers are up to 20 cm across.
The style is red and the stigma lobes yellow.
The fruit are oblong, red berries.