Phragmipedium section Phragmipedium Rolfe
in The Orchid Review 4: 330, 1896.

Synonyms :
   Cypripedium section Caudata Kraenzlin in Orch. Gen. et Sp. 1: 13, 1897.
   Paphiopedilum section Phragmipedium (Rolfe)V.A. Albert & Börge Pettersson in Lindleyana 9(2): 137, 1994.

Included :
   Cypripedium section Uropedium O. Ktze. in Lex. Gen. Phan. 159, 1903.

Type species :
   Phragmipedium caudatum (Lindley)Rolfe.

Characteristics : The species of this section are characterized by the very long petals, which are much longer than the sepals. They reach their final length only days after the flower has opened. The flowers on one inflorescence all open almost at the same time.

Species : According to Leslie A. Garay (1979) this section contains four species. Later on in 1984 Phrag. exstaminodium was described and added to this section. Phrag. caudatum is the only member of this section which is by all botanists indisputably recognized as a true species. The status of the other members varies considerably. Especially Phrag. wallisii and Phrag. warscewiczianum are still subjects for debate.
All the species in this section show a great resemblance to one another, which could mean that they are closely related. Studies by Karasawa (1980) show that all species known at the time have a chromosome count of 2n = 28. The research by Frank Stermitz (1981) concerning the alkaloid content of the species show, because of equal values, a very close relationship between Phrag. wallisii and Phrag. lindenii. Whereas with Phrag. caudatum and Phrag. warscewiczianum no alkaloids could be demonstrated. Somewhat later Stermitz also researched Phrag. exstaminodium material for its alkaloid contents, but none was found.
At the moment the separation of the various forms is most of the time based on the shape of the staminode. The problem with that is, that for one there is a form which lacks a staminode and two, because the shape of the staminode with the other forms varies considerably all together.
Olaf Gruss (1993) says, based on the current knowledge, that it is reasonable to classify the members of this section as three species and two varieties. And that is the ranking I will use for the time being.

Taxonomic history :
 
caudatum
warszewiczianum
popowii
exstaminodium
lindenii
Veitch
1887-1894
Stein
1892
Pfitzer
1903
Fortin
1975
L.A. Garay
1979
Schoser
1983
Hennessy & Hedge
1989
L.M. McCook
1989
C. Cash
1991
O. Gruss
1993
L.M. McCook
1998
O. Gruss
2003
Braem & al.
2004
Cypripedium caudatum Paphiopedilum caudatum Phragmopedilum caudatum caudatum caudatum caudatum caudatum caudatum caudatum caudatum caudatum caudatum caudatum
Cypripedium caudatum var. wallisii Paphiopedilum caudatum var. wallisii Phragmopedilum caudatum var. wallisii caudatum var. wallisii wallisii wallisii wallisii wallisii wallisii caudatum var. wallisii wallisii caudatum var. wallisii warszewiczianum
Cypripedium caudatum var. warscewiczii Paphiopedilum caudatum var. warscewiczii Phragmopedilum caudatum var. warscewiczianum caudatum var. warscewiczii warscewiczianum warscewiczianum warscewiczianum caudatum warscewiczianum caudatum var. warscewiczianum caudatum caudatum var. warscewiczianum popowii
(unknown entity) (unknown entity) (unknown entity) (unknown entity) (unknown entity) (unknown entity) (not mentioned) exstaminodium (not mentioned) exstaminodium exstaminodium exstaminodium exstaminodium
Cypripedium caudatum var. lindenii Paphiopedilum caudatum var. lindenii Phragmopedilum caudatum var. lindenii caudatum var. lindenii lindenii lindenii lindenii lindenii lindenii lindenii lindenii lindenii lindenii