A Grammatical Dictionary of Botanical Latin

Lacuna,-ae (s.f.I), abl.sg. lacuna, nom. pl. lacunae, acc.pl. lacunae, dat. & abl.pl. lacunis; a gap, void, chasm, cleft, opening, cavity, a hollow place; a pool; “a large, deep depression or excavation” (Lindley); “1. an air-space in the midst of tissue; 2. a depression on the thallus of a Lichen; 3. applied to the vallecular canals of Equisetum” (Jackson); (fungi) “a hole or hollow” (Ainsworth & Bisby); (fungi) “a depression” (S&D); the cavities that develop in rotted wood [> L. lacuna,-ae (s.f.I), “a ditch, pit, hole; especially a place where water collects, a pool, pond; a hollow, cavity, opening, chasm, cleft; a dimple; a gap, void” (Lewis & Short)]; cf. foramen,-inis (s.n.III); see cavity; see pit;

1. opening; a hole, fissure; (in fungi) “a hole or hollow” (Ainsworth & Bisby); implying roundness; cf. fenestra,-ae (s.f.I) and fenestratus,-a,-um (adj.A);

- [mosses] perist. dentes lanceolato-subulati trabeculati, inter trabes singulas medias lacuna s. fissura angusta pertusi, (Mueller), the teeth of the peristome [peristomii] lanceolate-subulate, trabeculate [i.e. with projecting cross-bars], between the middle individual cross-bar pierced through with a gap or [s.= seu] split.

[algae] coenobium liberum, sistens laminam orbicularem (rarius ellipticam), coronulae, stellae vel rotulae similem, aut continuam, aut lacunis intercellularibus interruptam (pertusam, clathratam) (Braun), colony free, exhibiting an orbicular lamina (more rarely elliptic), similar to a little crown, star or little wheel, either continuous, or interrupted (perforated, clathrate [i.e. latticed] by intercellular lacunae.

2. fissure, gap, chink; a chink is a crack, fissure, crevice, a surface or boundary split or burst, as from inside pressure;

- [algae] frons hic illic rumpitur, et expansione circa factam lacunam continuante, margines foraminis involvuntur, nova foramina oriuntur usque dum denique tota frons reticulatim perforata est (Agardh), the frond here and there is bursted, and with the expansion continuing around the gap that is made, the margins of the foramen are folded inward, while a new foramen arises, until finally the whole frond is perforated in a network.

Lacuna,-ae (s.f.II): a large cosmopolitan genus of animals called Chinks that is the type of the family Lacunidae” (WIII); Keyhole Limpet; “any of a family (Lacunidae) of conical marine snails having a slit (i.e. fissure, lacuna) on the columella opposite the aperture” (WIII); implying linearity.

3. lacuna, “an air-space in the midst of tissue” (Fernald 1950), a hollow, air-space in tissue, a cavity; “a blank space: gap, hole; ... one of the spaces among the tissues of lower animals that serve in place of vessels for the circulation of the body fluids” (WIII); see cavity.

NOTE: an elongate cavity is a canal or channel, hence lacuna,-ae (s.f.I) is “applied to the vallecular canals of Equisetum” (Jackson); a gap in the protoxylem resulting from breakdown of protoxylem elements during elongation of a root or shoot - called also carinal canal (WIII); cf. canal, channel;

Cavities: “Tubular openings: Open spaces of the pith, Lacunae, Cavitates aereae, Vasa pneumatica, Receptacula aerea accidentalia. Cavities filled with air, frequently found in the cellular texture, formed by rupture or absorption.

a. Lacunae irregulares: found in the middle of the fleshy parts of plants.

b. Lacunae fistulosae: occupy the center of the stalk, and render it hollow like a flute. Gramineae.

c. Lacunae regulares. Occupy the center of the stem of water plants, the cells being disposed in a regular order. Scirpus.

d. Lacunae cellulares. Large cavities, of which the sides are themselves composed of cellular texture. Sparganium.” (S. F. Gray).

NOTE: sometimes the lacunae are large cells differentiated by their size and clarity, e.g. hyalocysts, from the surrounding smaller, denser, colored cells; sometimes also called fenestrations (windows), but which are not open, hence membranaceous lacunae;

- [Sphagnum] folia sursum utraque superfìcie lacunis membranaceis instructa (Warnst.), the leaves, upwardly and beyond with the surface provided with membranaceous gaps.

- [algae] fila cellulas rotundatas magnas (an potius lacunas) minoribus repletas circumdantia, versus superficiem ut plerumque fastigiata, et stratum externum formantia (Agardh), the filamens surround large, rounded cells (or rather lacunae) filled with smaller ones, so that usually they are fastigiate [i.e. having parallel, massed, upright branches] toward the surface and form an outer layer.

- silicula compressa fere cuneata, apice lacunas duas vacuas gerens (DeCandolle), the silicle compressed, almost cuneate, at the apex bearing two empty cavities.

- [Myagrum] silicula compressa fere cuneata, apice lacunas duas vacuas gerens (DeCandolle), the silique compressed, almost wedge-shaped, at the apex bearing two empty cavities.

4. (in lichens) one of the small pits or depressions on the thallus of certain lichens; (in pollen), a depressed space or pit on the outer surface of a pollen grain; see depression; one of the meanings of the adj. lacunosus,-a,-um (adj.A) (see below) is ‘pitted.

- albumine aequabili v. extus lacunoso (B&H), with the albumen even or the outside pitted.

Cladonia lacunosa (lichen); Helvella lacunosa, a mushroom with a deeply ribbed stipe with deep gaping pits or cavities.

5. (geographical) a hole, ditch, pit, a pool, pond, a body of water that moves (such as up and down), opp. the stagnum,-i (s.n.II), q.v.; see lama, lustrum, see pool; see tarn.

- in lacunis silvaticis habitat, it dwells in woodland pools.

- habitatione in marginibus lacuum atque ad lacunas montanas ordinate inundatas distinguenda, to be distinguished by the habitat on the margins of lakes and also at mountain pools regularly (periodically) inundated.

- lacuna montana, a tarn or mountain pool.

- lacuna, id est aquae collectio, a lacu derivatur, quam alii lamam, alii lustrum dicunt, a lacuna is a collection of water, derived from a lake, which some call a lama, others a lustrum.

- habitatione in marginibus lacuum atque ad lacunas montanas ordinate inundatas distinguenda, to be distinguished by the habitat on the margins of lakes and also at mountain pools regularly (periodically) inundated.

NOTE: the word ‘lagoon’ derives from L. ‘lacuna,’ meaning a smaller water body, usually saline, associated with a larger one, the sea, a lake, etc. and separated from it by some barrier, but are often connected with it, as when the barriers are only islands. The word in this sense is related to number 5, above; for ‘canal’ see number 3 above;

- Hab. in lacuna exteriori Véneta natantem (Agardh), it grows floating in an outer Venetian lagoon.

- [algae] alga in Veneta lacuna splendidissima (3-4 pedalis) (Agardh), alga in a Venetian lagoon [i.e. canal] most magnificent [3-4 feet).

NOTE: Air Cavities.—In water-plants the intercellular spaces are frequently of large size, and bounded by a number of small cells regularly arranged by which they are prevented from communicating with one another, or with the external air ; they are then commonly termed air cavities. In such plants these cavities fulfil the important services of enabling them to float, and of supplying their interior with air. In other instances we find large air cavities, as in the stems of Grasses and Umbelliferous plants, which have been formed by the destruction of their internal tissues by the more rapid growth of the outer portions; these large cavities are termed lacunae, and appear to have no special functions to perform. (Robt. Bentley: A MANUAL OF BOTANY. 1887).