Food Pyramid
By Brian Tivol

Each of the clued words is six letters long and has a "pyramid"
  pattern: one letter appears once, another twice, and another thrice.

    An armchair for two                                 : SETTEE
    Cafeterias for soldiers                             : MESSES
    Common black condiment                              : PEPPER
    Considered                                          : DEEMED
    First-generation Japanese immigrants                : ISSEIS
    Gum arabic's source                                 : ACACIA
    The jacket-plum's genus                             : PAPPEA
    Married                                             : WEDDED
    Mei and Satsuki's wondrous neighbor                 : TOTORO
    An overdue debt                                     : ARREAR
    Part of a baseball game                             : INNING
    A Scottish lowland                                  : LALLAN
    A servant in charge of linens and finger bowls      : EWERER
    Severe illnesses caused by toxin-producing bacteria : SEPSES
    Site of museum with Yellow Calf's headdress         : ETHETE
    Spicy sauces for tortilla chips                     : SALSAS
    Swahili for watermelon                              : TIKITI
    Taste, and its four less important friends          : SENSES
    To chew with budding incisors                       : TEETHE
    To venerate and adore                               : REVERE
    Vomiting episodes                                   : EMESES
    What a dog says, or the manner a snooty dog has     : BOWWOW
    Where the Israelites went after fleeing Egypt       : CANAAN
    Wobble                                              : TEETER
    Yoga positions                                      : ASANAS

  This list creates some triplets of letters that can be numbered
  1-2-3.  You must determine which triplet goes with which
  triple-blank, put the appropriate letters in the numbered blanks,
  and spell the following message:

    TO REAP THE
    ANSWER, PRESENT
    SEVERAL SNACK
    ITEMS. WE DESIRE
    TWO BEARING
    THEMED, SPECIAL
    NAMES.

  (The order is: Totoro, Pappea, teethe, asanas, ewerer, pepper,
  senses, settee, revere, salsas, canaan, tikiti, messes, wedded,
  Isseis, teeter, bowwow, arrear, inning, Ethete, deemed, sepses,
  acacia, lallan, emeses.)

  In addition to the PEPPER, SALSAS, or TIKITI, I expect to see a lot
  of BANANAs and PAPAYAs.  Maybe even a PIPPIN or some REESE'S.
Archivist's note: The answer is PLUTONIUM.