Three of the earliest Roman liturgical books, the Gelasian Sacramentary (7th c.), and both the Paduan (7th c.) and the Hadrian (8th c.) editions of the Gregorian Sacramentary already call the Sunday before Easter Dominica in Palmis ("Sunday for Palms") or Die dominico ad Palmas. Even so, none of these documents explicitly mention any observances of palm rites, which were by the time already being performed in various parts of Christendom. The references to palms is absent in the propers, and in all the Roman Epistolari and Evangeliari of the period - in fact, the original title for the day probably did not mention palms at all, since the rite did not probably reach Rome until about the tenth century. In Rome, Palm Sunday was simply Passion Sunday, due to the fact that the Passion account from Matthew's Gospel (chapters 26-27) was read on this day. After the Gospel is read, the pope then usually gave a sermon on the first half of the account, postponing his explanation of the remainder to the following Wednesday.
Such a ceremony had already existed in Jerusalem as early as the 4th century, as testified to by the pilgrim Egeria:
Accordingly at the seventh hour all the people go up to the Mount of Olives, that is, to Eleona, and the bishop with them, to the church, where hymns and antiphons suitable to the day and to the place are said, and lessons in like manner. And when the ninth hour approaches they go up with hymns to the Imbomon, that is, to the place whence the Lord ascended into heaven, and there they sit down, for all the people are always bidden to sit when the bishop is present; the deacons alone always stand. Hymns and antiphons suitable to the day and to the place are said, interspersed with lections and prayers. And as the eleventh hour approaches, the passage from the Gospel is read, where the children, carrying branches and palms, met the Lord, saying; Blessed is He that cometh in the name of the Lord (Matthew 21:9), and the bishop immediately rises, and all the people with him, and they all go on foot from the top of the Mount of Olives, all the people going before him with hymns and antiphons, answering one to another: Blessed is He that cometh in the Name of the Lord. And all the children in the neighbourhood, even those who are too young to walk, are carried by their parents on their shoulders, all of them bearing branches, some of palms and some of olives, and thus the bishop is escorted in the same manner as the Lord was of old. For all, even those of rank, both matrons and men, accompany the bishop all the way on foot in this manner, making these responses, from the top of the mount to the city, and thence through the whole city to the Anastasis, going very slowly lest the poeple should be wearied; and thus they arrive at the Anastasis at a late hour. And on arriving, although it is late, lucernare takes place, with prayer at the Cross; after which the people are dismissed.In the West, it appears for the first time in the Liber Ordinum, a liturgical book of the Mozarabic Rite containing practices of the fifth to seventh centuries; both the blessing of palms at the altar and a subsequent procession with palms are mentioned. In the North Italian-Celtic Bobbio Missal (7th-8th century) a prayer for "the Blessing of Palms and Olives on the altar" is provided, but it says nothing about a procession afterwards; it does, however, indicate that the laity took palms home with them "piously with devotion." In the next century, the liturgist Amalarius of Metz apparently described the custom in his native Gaul: "In memory of this [our Lord's entry into Jerusalem] we are accustomed throughout our churches to carry branches and to cry Hosanna." It was during this same period that Theodulf, Bishop of Orléans (ca. 750/60-821) composed the hymn Gloria, Laus et Honor. A procession is described in the tenth-century Regularis Concordia, a document produced in Winchester detailing the practices of English Benedictine monasteries:
...the gospel Turba multa [John 12:12-19] shall be read by the deacon as far as the words "Behold, the whole world is gone after him": the blessing of the palms shall follow. After the blessing the palms shall be sprinkled with holy water and incensed. While the children begin the antiphons Pueri Hebraeorum the palms shall be distributed. Then the greater antiphons shall be intoned and the procession shall go forth. As soon as the mother church is reached the procession shall wait while the children, who shall have gone on before, sing Gloria laus with its verses, to which all shall answer Gloria laus, as the custom is. When this is finished the cantor shall intone the respond Ingrediente Domino and the doors shall be opened.It is more likely that the arrival in Rome of the Romano-Germanic Pontifical compiled in in St. Alban's Abbey, Mainz, under the reign of William, Archbishop of Mainz, in the mid-tenth century, would have led to the introduction of the Procession of Palms into the Roman liturgy, for just such a ceremony is described at great length in this work (Ordo de die Palmarum). The pontifical itself had a decisive influence over the Roman liturgical books of the twelfth-thirteenth centuries - such ceremonies already appear in the Roman Ordines 11 and 12.
The propers of the day from the Gelasian Sacramentary:
DOMINICA IN PALMISFrom the Hadrian Sacramentary:
De Passione Domini.
(Omnipotens sempiterne) Deus, qui humano generi ad imitandum humilitatis exemplum, Salvatorem nostrum et carnem sumere et crucem subire fecisti, concede (nobis) propitius ut et patientiae eius habere documentum et resurrectionis eius consortia mereamur, Christi Domini nostri. Qui tecum vivit et regnat Deus in unitate Spiritus sancti, per.
Deus, quem diligere et amare iustitia est, ineffabilis gratiae tuae in nobis dona multiplica: et [ut] qui fecisti nos morte Filii tui sperare quod credimus, fac nos, eodem resurgente, pervenire quo tendimus. Per.
Ipsa maiestati tuae, Domine, fidelis populus commendet oblatio, qui per Filium tuum reconciliavit inimicos, Iesum Christum Dominum nostrum. Qui tecum uiuit et regnat Deus in unitate Spiritus sancti, per omnia saecula saeculorum.
Sacro munere satiati, supplices te, Domine, deprecamur, ut qui debite servitutis celebramus officio, salvationis tuae suscipiamus augmentum. Per.
Purifica, quaesumus, Domine, familiam tuam, et ab omnibus contagiis pravitatis emunda, ut redempta vasa sui Domini passione, non spiritus immundus rursus inficiat, sed salvatio sempiterna possideat. Per.
DIE DOMINICO IN PALMAS
Ad Sanctum Iohannem in Lateranis.
Omnipotens sempiterne Deus, qui humano generi ad imitandum humilitatis exemplum, Salvatorem nostrum carnem sumere et crucem subire fecisti, concede propitius ut et patientiae ipsius habere documenta et resurrectionis consortia mereamur, Per.
Super oblata.Concede, quaesumus, Domine, ut oculis tuae maiestatis munus oblatum, et gratiam nobis devotionis obtineat, et effectum beatae perennitatis acquirat. Per.
Per huius, Domine, operationem mysterii: et vitia nostra purgentur, et iusta desideria compleantur. Per.