There are 13 members of the Maryland General Assembly who unquestionably are more powerful than the others. They control the flow of legislation, decide who serves on what committee and generally make the rules of the game for the next 89 days in Annapolis.

Collectively, they are called the "leadership": the Senate president, the House speaker and the major committee chairmen in each chamber.

They are a strikingly homogenous group. White males all, they tend to be lawyers from urban backgrounds, representing either Baltimore or the Baltimore and Washington suburbs. Neither poor nor very rich, they are somewhere in that broad category known as the midddle class. On the average, they are over 50 years old. All Democrats, none could be called a "crusader" for any cause or ideology. in fact, most are distinguished by their ability to get along without making enemies, without shaking things up.

Sometime over the last decade, all of these 13 men worked their way into key positions in the 188-member Maryland legislature. Some are effective in their postiions, others decidedly less so. Some are deferred to by their fellow legislators, others are frequently circumvented, and others have learned how to make confrontation with their colleagues an art. None can be ignored. John Hanson Briscoe

The speaker of Maryland's house of Delegates sports dark sideburns and sport coats evocative of the 1970s, and has a courtly manner and drawl evocative of 19th century southern Maryland. A 28-year-old whiz kid when he was papointed to the legislature to fill a vacancy 16 years ago, Briscoe has advanced over the years by doing things the way they have always been doing in Annapolis.

In practice, this has meant that Briscoe, who keeps a law practice going at his home in rural St. Mary's County, never has strayed too far from the mainstream of thought in the legislature. His philosophy as the leader of the House seems simple. Things should be orderly, legislation should be moved along - or killed - efficiently, and nothing should change too radically. His colleagues tend to agree that he is effective in his pursuit of those goals.

Like so many other members of the General Assembly's leadership, he was an admirer and often a follower of suspended Gov. Marvin Mandel. he had a continuing feud with madel's second wife - the former Dorsey - Jeanne stemming form the days when the Briscoe family and the Dorsey family were competing forces int he small world of St. Mary's County politics. That feud surfaced in recent years in quiet dusputes between the two over who would influence Mandel's attitudes on St. Mary's political matters. Briscoe tended to lose those fights.

Like a good soldier in the midst of a steady, solid career, Briscoe seems to be looking forward to the next logical step: an appellate ljudgeship. Benjamin L. Cardin

This genial, brainy young attorney from Marvin Mandel's old district in northwest Baltimore lhas held the chairmanship of the Ways and means Committee for only three years, but in that time, he has gained wide respect for his understanding and handling of the complex tax legislation that passes through his hands.

At 35, Cardin is the youngest of the 13 men who make up the legislative leadership. He nevertheless is among the most influential; a rising star who is considered a leading candidate for speaker of the House when Briscoe chooses to retire, and a possible future governor.

He has a lot of things going for him in a body as clubby and set in its ways as the legislature - he is the scion of an old Baltimore political dynasty, he is regarded as a team player who picks his legislative fights carefully.

While Cardin's legislative style has won him the respect of old-guard legislators, he also maintained a liberal image in his constituency in the northwest corner of Baltimore: affluent-high-turnout, predominantly Jewish section that wields political power out of proportion to its population. Joseph E. Owens

Joe Owens, 59, takes pains to separate himself from the conventional image of a Montgomery County legislator. He does not champion liberal ideals or espouse vast legislative reforms or give speeches denouncing vote-trading.

Aside from the reinstitution of the death penalty, the only cause Owens probably would champion would be a bill abolishing all causes.

As chairman of the House Judiciary Committee - which considers all bills involving changes in criminal law and procedure - Owens is the legislature's most accomplished skeptic. His committee is known as "the place bills go to die" and he takes positive pride in its kill ratio.

In most things, this white-haired curmudgeon of the legisalture is a classic, antigovrnment conservative. He is a retired army lieutenant colonel, deferred to by most members of the House.

Owens enjoys lauging at the antics around him but tends to live apart from his colleagues in a comfortable middle world of his own. He is neither a reformist zealot, nor a part of the chummy clubbiness of the Baltimore-based organization politicians. Charges J. Krysiak

Charles J. Krysiak was born in Baltimore, got his law degree in Baltimore, and generally likes the way they do things in Baltimore. Chatty and unpretentious, he takes pride in being an organization pol. The only thing he would rather be, apparently, is a judge.

The 40-year-old Krysiak, a proud member of many Polish-American groups, was first sent to the legislature by his heavily ethnic East Baltimroe constituents in 1967. When he got to Annapolis, he fell right into the rhythm of things.

A religios Catholic, who firmly gives up alcolhol every year for Lent (and thus cannot go out drinking for most of the legislative session) Krysiak also is sometimes equally fervent in the zeal with which he combats what others consider legislative reforms. John S. Arnick

John Arnick takes as a personal insult any suggestion that the maryland HOuse of Delegate is not well run or that maybe the State Senate is run better. As majority leader, he is in many respects a cheerleader for his colleagues as wella s his party's enforcer.

A lawyer who represents a blue collar section of Baltimore County known as Dundalk, he tends to agree that there is littel reason to make major changes in the way things are done in Annapolis.

When things have gone against him, he has been known to rise in the House and publicly repeat the old political addage: "Don't get angry. Get even." Usually, he does get even. A few years ago, he led a wholesale slaughter of bills introduced by a Senate colleague who had bucked the prevailing sentiment on the question of legislative redistricting.

Arnick is one of the General Assembly's most sociable members and is a regular - snappily dressed - at parties and watering holdes.

He is chariman of the Environmental Matters Committee of the House that often enrages environmentalists who believe the committee is stacked against them. John R. Hargreaves

Hargreaves, 64, is the chairman of the House Appropriations Committee, which considers the governor's budget as its main business each legislative session.

He is thus best known for the necessarily tediousa nd interminable presentations he give as the House considers the multibillion dollar document. For days on end, his nasal voice echoes throught the chambers and hallways of the Statehouse.

Although he is a business consultant now, he was an Eastern Shore poultry raiser for most of his career and once was the mayor of Federalsburg.

He is the Shore's only committee chairman and the only House leader with a largely rural constituency. John J. Wolfgang

The word "quiet" comes up again and again when the name of this 51-year-old Prince George's County lawyer is mentioned. His Economic Matters Committee is the scene of frequent struggles over special interest banking and liquor legislation and the target of the numerous consumer advocates who descend on Annapolis each Janurary.

Wolfgang has served in the House since 1971, when he was appointed to replace a legislator who moved up to the senate.

Wolfgang has been trying to obtain a judgeship but has been passed over so far by Prince George's County powers. Senate Steny H. Hoyer

Steny Hoyer leaned back in his chair yesterday, nodding his head and smiling politely as his colleagues in the State Senate paid him tribute after tribute. For the fourth year in a row, the young lawyer was being re-elected to one of the key posts in the General Assembly - the presidency of the Senate.

Hoyer was looking beyong that. For this thin blond 38-year-old always has managed to find a way to get into important jobs before anyone expected him to. After one year in the General Assembly, he was elected to head the Prince George's delegation. Then, in 1975, he skipped right over several rungs on the leadership ladder to become Senate president. By next january, he would like to be governor. Roy N. Staten As the Senate rushed its way through its skimpy first-day agenda yesterday, Roy Staten seemed to be right back in the forefront of things, red-faced, smiling, nodding to the right and left of his front-row seat as he silently directed the flow ofmotions and seconds.

Appearances probably were decieving. When Marvin Mandel left the governor's office, Staten lost his occupation. Though he still caries the title of majority leader, the large pleasantman with the chipmunk jowls has relinquished a far more important, though informal post - the job of being the governor's right-hand man.

Even last year, with mandel still occupying the executive office, Staten's authority was starting to crumble.

That does not mean that the raspy 64-year-old from the eastern, indutrial section of Baltimore County will not be heard this session. As majority leader, States still will be doing a lot of talking, on the Senate floor, in the Senate corridors, and in the restaurants nearby.

The question is who will be listening. Harry J. McGuirk

There always seems to be a peaceful, slightly knowing smile playing about the lips of Harry McGuirk, the short dapper real estate salesman from south Baltimore. It all comes foom his tending to concentrate on two things when he is in Annapolis: staying unruffled, and knowing everything that is going on.

In this way, without ever seeming to hurry, without ever seeming to push anyone else out fot he way, this former head of a Baltimore Elks Lodge has become probably the most powerful, most effective member of Maryland's State Senate.

On paper, McGuirk's job is to chari the Senate Economic Committee. In fact, his skills go far beyond that. For one thing, McGuirk - one of the feew nonlawyers in the legislative leadership - has made himself a master of legal language, to the point of being able to change the meaning of an entire billby changing a comma to a semicolen, or by adding a seemingly innocuous amendment. James Clarke Jr.

Caught as he is in the midst of the lawyers and businessmen. Clark takes pride in being able to tell people tha the is a farmer - even if his Howard County district has a lot more in common now with suburban Montgomery County than it does with a cornfiedl.

Nonetheless, Clark, a 59-year-old attorney has for years affected a country-boy style, interspersing his down-home conversation and jokes with the same very canny political maeuvering that has lifted him to the chairmanship of the Senate Finance Committee. J. Joseph Curran Jr.

If Hollywood talent were ever to come to Annapolis looking for a legislator straight out of central casting, they probably would end up taking Joe Curran back west with them. More perhaps than anyone else in the 183-member legislature, Curran, with his wavy brown hair, square face and tall, solid build, looks the part.

He acts the part, too - at elast he part as government textbooks might describe it. After nearly two decdes in the legislature, this lawyer from Baltimore like Cardin, the product of a political family - has acquired a reputation for being one of the fairest-minded lawmakers in the state. Edward T. Conroy

Edward Conroy, one of the two Prince George's County representatives among the half-dozen Senate leaders, does not command the same kind of attention as does his compatriot, Steny Hoyer. Tall, heavy and genial, Conroy seems to be liked by most of his colleagues - but not looked to for political help or advice in an emergency.

Chairman of the constitutional and public law committee, Conroy is in a position to take the stewardship over most government reorganization bills, all of which tend to be sent to his committee. He takes more interest in veteran's issues, an interest perhaps spawned by his experience in the Korean war, which left the 48-year-old without the use of his left arm.