(Lat.: ‘fold’).
In Western chant notations the name used in the 13th and 14th centuries for liquescent neumes. It describes their usual shape: a single stroke doubling back on itself to make a ‘U’ or inverted ‘U’, thicker at the curve. The plica is a two-note neume, containing the pitch where the plica was placed on the staff plus a higher (‘U’ shape) or lower (inverted ‘U’) note. The second note was semi-vocalized to provide a passing or anticipatory note before the next pitch. The semi-vocalization was most commonly practised on the consonants ‘l’, ‘m’, ‘n’ and ‘r’, before another consonant (2452 out of 3500 cases in the study in PalMus, 1st ser., ii, 1891), sometimes when they were the only consonant between vowels; on the second vowel of diphthongs; on the consonant pair ‘gn’; sometimes on ‘d’ and ‘t’ at the ends of words (particularly et, sed, ut); sometimes on soft ‘c’ and soft ‘g’ (before ‘e’ and ‘i’); sometimes also on ‘d’, ‘s’, ‘t’ and ‘x’, before other consonants; and on ‘i’ or ‘j’ when used as a consonant.
While early writers on neume shapes and names (see Huglo) called the ascending form epiphonus and the descending form cephalicus, 13th-century theorists used the term ‘plica’. Thus Jehan des Murs (GerbertS, iii, 202):
Clives,
plicae, virga, quilismata, puncta, podati,
Nomina sunt harum; sint pressi consociati.
The plica retained its basic function of indicating liquescence in all plainchant manuscripts and in most sources containing polyphony and non-mensural secular monophony until the 14th century. The situations in which Mocquereau found liquescent neumes used in 10th- and 11th-century manuscripts (see PalMus, 1st ser., ii, 1891) are distinguished in the same way in later sources (with minor differences resulting from different pronunciation practice, to which, in fact, liquescent neumes are a guide). Of later theorists only Lambertus (Pseudo-Aristotle) attempted a description of the method of voice production involved (CoussemakerS, i, 273): ‘The plica is sung by narrowing or closing the epiglottis while subtly including a vibration of the throat’; this seems to be a picturesque way of saying that the forethroat is formed as for consonants while the vocal chords are still vibrating.
In Parisian repertories of polyphony of the early 13th century, however, the plica was also used in melismatic music, without liquescent function. Five of the rhythmic modes, which were the basis of the method of indicating rhythm in this music, did not provide for a note on at least one beat of a ternary measure (i.e. one quaver out of every three in 3/8 transcription; or two out of six in 6/8 transcription). Ex.1 shows how plica strokes added to patterns of 1st- and 2nd-mode ligatures provide these notes (see Apel, pp.228–9, for more complex examples). The plica most often implies an added note at the interval of a 2nd. Definite instances of larger intervals are rare, one such being found in the conductus Deduc Syon uberrimas: in E-Mn 20486 on the syllable ‘-tas’ of ‘gravitas’ there is a two-note descending ligature d–G (f.84r, staff 4); in D-W 677 there is a plica on d with a slight thickening at the end of the stroke on G (f.160r [151r], staff 10); while I-Fl 29.1 and D-W 1206 have a plica with stylized square note head and a long descending tail to the right (f.336v, staff 4, f.94r, staff 6, respectively).
In the second half of the 13th century discrete note shapes were evolved for plica longa and plica brevis, to complement the standard long and breve shapes; Table 1 gives the commonest forms. The Parisian repertories of the second half of the 13th century are, however, largely of syllabic music (i.e. motets), and the plica retained its basic function of denoting liquescence. Walter Odington, who called it ‘semitonus et semivocalis’ (CoussemakerS, i, 236), preferred to use the longer method of writing 6th-mode passages (continuous breves): ‘certior est et acceptior’ (CoussemakerS, i, 245), presumably to avoid confusion between the two functions.
The plica was frequently preceded by another note of the same pitch; the reason for this is not always clear. The group can usually be confidently transcribed as equivalent to a long (crotchet or dotted crotchet) rather than a breve (quaver), but this is by no means a universal rule (see Tischler). It was to some extent interchangeable with the simple plica, with a two-note ligature or with a three-note group in which the first two notes were of the same pitch. A comparison of the notation of D-W 677, 1028, E-Mn 20486 and I-Fl 29.1 for the tenor parts of the 17 polyphonic conductus they have in common shows 50 or so simple plicae found alone above a single syllable, 100 or so ‘compound’ plicae, and 170 or so binaria or single note + binaria, in any one manuscript: 12–15% are found in an alternative form in one or more of the other three manuscripts. E-Mn 20486 shows a preference for simple plicae, D-W 1028 for binaria or single note + binaria; sometimes D-W 677 and E-Mn 20486 use a binaria with elongated first element where the other manuscripts have a compound plica or single note + binaria. More detailed statistics both depend on and help investigation of the layering of the repertory as a whole.
The single note + binaria is the usual form in square staff notation of the pressus (descending) and pes quassus (ascending) compound neumes. Although these neumes originally entailed a special manner of performance (Jehan des Murs said the pressus should be performed evenly and swiftly; GerbertS, iii, 202), they have no special shape in, for instance, Parisian 13th-century chant manuscripts, to draw attention to this characteristic. Kuhlmann (p.111) suggested that in Parisian polyphony the note-group denoted a vibrato, being what Jerome of Moravia called flores (CoussemakerS, i, 91–2). At any rate the compound plica was usually used in situations where liquescence was appropriate.
The Fathers of Solesmes (PalMus, 1st ser., ii, 1891) said that not every such situation was matched by a liquescent neume, but did not give figures to show how often. Table 2 gives statistics for the tenor parts of the three- and two-part conductus in I-Fl 29.1; it shows the number of times a syllable ending ‘l’, ‘m’, ‘n’ or ‘r’ and followed by another consonant (words such as salve, omnes, cantat, virgo) is matched by a simple plica, a compound plica, a binaria or a single note + binaria (ascending or descending forms). The use of binaria may possibly be a tendency in later pieces or in those that are more certainly Parisian; separate figures are therefore given for pieces that are also found in other sources and for unica, to show approximately how the repertory of the manuscript is divided (for further evidence see Hiley). The polyphonic pieces of the Roman de Fauvel (F-Pn fr.146), the last source in mensural music to use plicas to any great extent, still used the plica for liquescence.
A. Mocquereau: ‘Neumes-accents liquescents ou semi-vocaux’, Le répons-graduel Justus et palma, PalMus, 1st ser., ii (1891), 37–86
J. Pothier: ‘De la plique dans le plain-chant’, Revue du chant grégorien, iii (1895), 55–9 [summarized by P. Bohn, MMg, xxvii, 1895, p.47]
G.M. Suñol: Introducció a la paleografia musical gregoriana (Montserrat, 1925; Fr. trans., rev. and enlarged 2/1935)
H. Freistedt: Die liqueszierenden Noten des gregorianischen Chorals (Fribourg, 1929)
G. Kuhlmann: Die zweistimmigen französischen Motetten des Kodex Montpellier, Faculté de médecine H 196 (Würzburg, 1938)
W. Apel: The Notation of Polyphonic Music 900–1600 (Cambridge, MA, 1942, rev. 5/1961)
M. Huglo: ‘Les noms des neumes et leur origine’, EG, i (1954), 53–67
H. Tischler: ‘Ligatures, Plicae and Vertical Bars in Premensural Notation’, RBM, xi (1957), 83–92
H. Anglès: ‘Die Bedeutung der Plika in der mittelalterlichen Musik’, Festschrift Karl Gustav Fellerer (Regensburg, 1962), 28–39
D. Hiley: ‘The Plica and Liquescence’, Gordon Athol Anderson (1929–1981): in memoriam (Henryville, PA, 1984), 379–91
DAVID HILEY