O.Henry is describing a millionaire's estate:
"The Millionaire's palace occupied a lordly space. In front of it was a lawn close-mowed as a South Ireland man's face two days after a shave. At one side of it, and fronting on another street was a pleasuance trimmed to a leaf, and the garage and stables."


Webster's 1913 Dictionary

Definition: \Pleas"ance\, n. [F. plaisance. See {Please}.]
1. Pleasure; merriment; gayety; delight; kindness. [Archaic]
--Shak. ``Full great pleasance.'' --Chaucer. ``A realm of
pleasance.'' --Tennyson.

2. A secluded part of a garden. [Archaic]

The pleasances of old Elizabethan houses. --Ruskin.



I assume that "pleasuance" in the text is a typo.

These secluded parts of gardens offer such a sense of surprise and mystery. We have many pleasances at Maymont in Richmond.

I checked out your spelling and came across:

"Chaffy; resembling or consisting of paleae, or chaff; furnished with chaff; as, a paleaceous receptacle."

...for paleaceous

But because it is very, very late, I misread 'chaff' for 'cliff' and thought I'd found quite a wonderful definition! Time for bed!

I could find nought to confirm the typo supposition or otherwise, Bill. However, the info on variant forms of 'pleasure' is quite interesting, so I present it for your pleaceur:

[ME. plesir, plaisir a. OF. plesir, plaisir (12th c. in Littré), + Pr. plazer, Sp. placer, Pg. pracer, It. piacere, Com. Romanic substantival use of the vb. infin.:—L. placUre to please. By 1400, ple"sWr had become (in prose) "plUsir, "plUser, and its unstressed ending being confounded with that of words etymologically in -ure, e.g. measure, it was corruptly spelt and pronounced plesure, pleasure. The dialects have retained more eytmological forms in pleezer, plezzer ("pli;z@(r), "plEz@(r)).]
A. Illustration of Forms.

(a) 4–5 plesir, 5 plesyr, -yre, -ire, -ier, -yer; plaisir, playsir, -ire, -yr, -yre; pleasir, -ire, -ier, -yr, -er; pleeser; 5–6 pleser, -ere; 6 pleasire; 9 dial. pleezer, plezzer.
[...]
(b) 5 plaisur, playsur, -ure; 5–6 plesur; pleasur, -our (–7 Sc.); 5–7 plesure; 5– pleasure; 6 plesour, -oure, -owre, -ewre; pleasor, Sc. pleisour, -ure, pleissour, plessour, -uir, 7 pleaceur, Sc. pleassour, plessor.

[...] 3†b. A pleasure-ground. Obs.
[e.a.]


And I came across another lovely word in passing:

dicacity
[f. L. dicQx, dicQc-em, sarcastic (f. dic- stem of dWcSre to say, speak) + -ity.]

A jesting or mocking habit of speech; raillery, banter; pertness. (Sometimes after L. dWcSre: Talkativeness, babbling.)

OED2