From the Surname Database
Recorded in several spellings including Morrison, Morrieson, Morison, and Moryson, this is an Anglo-Scottish surname, which is almost equally popular in Ireland. It is the patronymic form of the surname Maurice or Morris, deriving from the Latin "Mauritius", and meaning swarthy, from "Maurus", a Moor. The popularity of the name was due in part to the fame of St. Maurice, martyred in 286 A.D. The given name Morris was introduced into Britain by the Normans, among whom it was popular. The personal name was recorded circa 1176 when one "Mauricius de Edligtona" was mentioned in the "Social and Economic Documents of London". It first appears as a surname in England in the 14th century (see below) in England, whilst Andreas Morison, a licenciate in law at St. Andrew's in 1463, was according to the church register of Brechin, the first recorded namebearer in Scotland. Other examples of early recordings include those of Nicol Morysone of Ruchtven, Scotland, in 1501, whilst Charles Morrison (circa 1752) first suggested conveying messages by electricity, and invented the first projector of the electric telegraph. A coat of arms was granted to Sir Richard Morrison, knighted at Dublin by Robert, Earl of Essex, and Lord-Lieutenant, on August 5th 1599. The first recorded spelling of the family name is shown to be that of Robert Morisson. This was dated 1379, in the Poll Tax records of Yorkshire, during the reign of King Edward 1st, 1272 - 1307. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.
http://en.wikipedia.org/wiki/File:Morrison_crest.png
Symbols The crest badge worn by members of Clan Morrison consists of the chief's heraldic crest and motto. By wearing this badge, clan members show their allegiance to their clan chief. The chief's motto is TEAGHLACH PHABBAY, which translates from Scottish Gaelic as "Pabbay family".[22] This motto refers to the chief's descent from the Morrisons of Ruchdi, who claim to descend from the Morrisons of Dun Pabbay, on Harris. The chief's crest is issuant from waves of the sea azure crested argent, a mount vert, thereon a battlemented wall azure masoned argent, and issuing there from a cubit arm naked proper, the hand grasping a dagger hilted Or.[22] The plant badge of Clan Morrison is driftweed.[19] There are several tartans attributed to the surname Morrison and Clan Morrison has an official clan tartan. This tartan was recorded by the Lord Lyon King of Arms on 3 January 1968. The tartan is based on a sett which was first found in 1935, when an old Morrison family bible was uncovered in a Black House which was to be demolished on Lewis. The piece of tartan was wrapped around the bible, and inside a note referencing the sett was dated 1745.[23][24] The Clan Morrison Society (of Scotland) tartan is a variant of the Mackay tartan. This Morrison tartan dates from about 1908-1909. The society chose to base their tartan on the Mackay because of a historical link between Morrisons and Mackays. This link stems from the marriage of Ay Mac Hormaid and the daughter of the Bishop of Caithness. The bride's dowry consisted of the lands of Durness and subsequently sixty Morrison families emigrated there in the 17th century.
http://en.wikipedia.org/wiki/Clan_Morrison
Septs
Owing to the long history, the inconsistency in anglicizing Gaelic names, and the changes in the English language over the centuries, many surnames of today can trace their ancestry back to the Morrisons. These are known as "septs" of the clan. Not all families with these "sept" names are necessarily Morrisons, however, as many chose (or were given) names that sounded like pre-existing English names. The primary septs most often recognized as being Morrisons are Gilmore, Brieve and MacBrieve. Other families that could be Morrisons include Breive, Gillamor, Gillemoire, Gillemor, Gillemore, Gillemur, Gillemure, Gilmer, Gilmoir, Gilmor, Gilmour, Gilmoure, Gilmur, Gilmure, Gylmor, MacBreive, MacGilmor, MacIllimhier, Moris, Morison, Morris, Morrieson, Morrison, Murieson, Murison and Murrison.