Definition of tracheids

"tracheids" in the noun sense

1. tracheid

long tubular cell peculiar to xylem

Source: WordNet® (An amazing lexical database of English)

Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.

View WordNet® License

↑

tracheids in Scrabble®

The word tracheids is playable in Scrabble®, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.

Scrabble® Letter Score: 15

Highest Scoring Scrabble® Play In The Letters tracheids:

TRACHEIDS

(162)

Seven Letter Word Alert: (34 words)

achiest, aitches, aridest, astride, cashier, chaired, charted, chaster, cithers, crashed, credits, cristae, dacites, dearths, directs, disrate, ditcher, ditches, dithers, drastic, hardest, hastier, hatreds, raciest, radices, redacts, richest, scathed, shadier, shirted, sidecar, threads, tirades, trashed

All Scrabble® Plays For The Word tracheids

TRACHEIDS

(162)

TRACHEIDS

(144)

TRACHEIDS

(108)

TRACHEIDS

(96)

TRACHEIDS

(76)

TRACHEIDS

(60)

TRACHEIDS

(60)

TRACHEIDS

(60)

TRACHEIDS

(51)

TRACHEIDS

(51)

TRACHEIDS

(50)

TRACHEIDS

(50)

TRACHEIDS

(48)

TRACHEIDS

(48)

TRACHEIDS

(48)

TRACHEIDS

(42)

TRACHEIDS

(40)

TRACHEIDS

(40)

TRACHEIDS

(38)

TRACHEIDS

(36)

TRACHEIDS

(36)

TRACHEIDS

(36)

TRACHEIDS

(34)

TRACHEIDS

(34)

TRACHEIDS

(34)

TRACHEIDS

(34)

TRACHEIDS

(34)

TRACHEIDS

(34)

TRACHEIDS

(32)

TRACHEIDS

(32)

TRACHEIDS

(32)

TRACHEIDS

(32)

TRACHEIDS

(30)

TRACHEIDS

(30)

TRACHEIDS

(30)

TRACHEIDS

(27)

TRACHEIDS

(25)

TRACHEIDS

(21)

TRACHEIDS

(21)

TRACHEIDS

(21)

TRACHEIDS

(19)

TRACHEIDS

(19)

TRACHEIDS

(19)

TRACHEIDS

(19)

TRACHEIDS

(18)

TRACHEIDS

(18)

The 200 Highest Scoring Scrabble® Plays For Words Using The Letters In tracheids

TRACHEIDS

(162)

TRACHEIDS

(144)

TRACHEIDS

(108)

DITCHER

(102 = 52 + 50)

CHAIRED

(102 = 52 + 50)

CHARTED

(102 = 52 + 50)

SCATHED

(102 = 52 + 50)

CRASHED

(102 = 52 + 50)

DITCHES

(102 = 52 + 50)

CHAIRED

(101 = 51 + 50)

CRASHED

(101 = 51 + 50)

SCATHED

(101 = 51 + 50)

DITCHER

(101 = 51 + 50)

CHARTED

(101 = 51 + 50)

DITCHES

(101 = 51 + 50)

CASHIER

(98 = 48 + 50)

RICHEST

(98 = 48 + 50)

CASHIER

(98 = 48 + 50)

CHARTED

(98 = 48 + 50)

CASHIER

(98 = 48 + 50)

DITCHES

(98 = 48 + 50)

RICHEST

(98 = 48 + 50)

CITHERS

(98 = 48 + 50)

DITCHER

(98 = 48 + 50)

CHASTER

(98 = 48 + 50)

CHASTER

(98 = 48 + 50)

RICHEST

(98 = 48 + 50)

SCATHED

(98 = 48 + 50)

CRASHED

(98 = 48 + 50)

DITCHER

(98 = 48 + 50)

AITCHES

(98 = 48 + 50)

CITHERS

(98 = 48 + 50)

DITCHES

(98 = 48 + 50)

ACHIEST

(98 = 48 + 50)

CITHERS

(98 = 48 + 50)

CHAIRED

(98 = 48 + 50)

ACHIEST

(98 = 48 + 50)

AITCHES

(98 = 48 + 50)

TRACHEIDS

(96)

SHIRTED

(95 = 45 + 50)

THREADS

(95 = 45 + 50)

HATREDS

(95 = 45 + 50)

DITCHER

(95 = 45 + 50)

DEARTHS

(95 = 45 + 50)

TRASHED

(95 = 45 + 50)

CHASTER

(95 = 45 + 50)

CHAIRED

(95 = 45 + 50)

CRASHED

(95 = 45 + 50)

SCATHED

(95 = 45 + 50)

AITCHES

(95 = 45 + 50)

CHARTED

(95 = 45 + 50)

HARDEST

(95 = 45 + 50)

CITHERS

(95 = 45 + 50)

ACHIEST

(95 = 45 + 50)

DITCHES

(95 = 45 + 50)

AITCHES

(95 = 45 + 50)

CASHIER

(95 = 45 + 50)

DITHERS

(95 = 45 + 50)

DITHERS

(95 = 45 + 50)

SHADIER

(95 = 45 + 50)

RICHEST

(95 = 45 + 50)

SHIRTED

(94 = 44 + 50)

DITHERS

(94 = 44 + 50)

THREADS

(94 = 44 + 50)

TRASHED

(94 = 44 + 50)

HARDEST

(94 = 44 + 50)

SHADIER

(94 = 44 + 50)

HATREDS

(94 = 44 + 50)

DEARTHS

(94 = 44 + 50)

CRASHED

(92 = 42 + 50)

DITCHES

(92 = 42 + 50)

CHARTED

(92 = 42 + 50)

CRASHED

(92 = 42 + 50)

DITCHER

(92 = 42 + 50)

CHARTED

(92 = 42 + 50)

CHAIRED

(92 = 42 + 50)

DITCHES

(92 = 42 + 50)

SCATHED

(92 = 42 + 50)

CHAIRED

(92 = 42 + 50)

DITCHER

(92 = 42 + 50)

CHAIRED

(92 = 42 + 50)

CHAIRED

(92 = 42 + 50)

DITCHES

(92 = 42 + 50)

HASTIER

(92 = 42 + 50)

CRASHED

(92 = 42 + 50)

SCATHED

(92 = 42 + 50)

CHARTED

(92 = 42 + 50)

CRASHED

(92 = 42 + 50)

DITCHES

(92 = 42 + 50)

CHARTED

(92 = 42 + 50)

SCATHED

(92 = 42 + 50)

CHARTED

(92 = 42 + 50)

SCATHED

(92 = 42 + 50)

DITCHER

(92 = 42 + 50)

CHARTED

(92 = 42 + 50)

CRASHED

(92 = 42 + 50)

SCATHED

(92 = 42 + 50)

CRASHED

(92 = 42 + 50)

DITCHES

(92 = 42 + 50)

DITCHER

(92 = 42 + 50)

CHAIRED

(92 = 42 + 50)

SCATHED

(92 = 42 + 50)

CHAIRED

(92 = 42 + 50)

DITCHER

(92 = 42 + 50)

CHASTER

(90 = 40 + 50)

CREDITS

(90 = 40 + 50)

HASTIER

(90 = 40 + 50)

AITCHES

(90 = 40 + 50)

DACITES

(90 = 40 + 50)

SIDECAR

(90 = 40 + 50)

DIRECTS

(90 = 40 + 50)

REDACTS

(90 = 40 + 50)

DRASTIC

(90 = 40 + 50)

RADICES

(90 = 40 + 50)

ACHIEST

(90 = 40 + 50)

SIDECAR

(89 = 39 + 50)

ACHIEST

(89 = 39 + 50)

CITHERS

(89 = 39 + 50)

CHASTER

(89 = 39 + 50)

CASHIER

(89 = 39 + 50)

RICHEST

(89 = 39 + 50)

HATREDS

(89 = 39 + 50)

ACHIEST

(89 = 39 + 50)

CHASTER

(89 = 39 + 50)

AITCHES

(89 = 39 + 50)

RICHEST

(89 = 39 + 50)

CASHIER

(89 = 39 + 50)

ACHIEST

(89 = 39 + 50)

CITHERS

(89 = 39 + 50)

AITCHES

(89 = 39 + 50)

CHARTED

(89 = 39 + 50)

DITHERS

(89 = 39 + 50)

CASHIER

(89 = 39 + 50)

RICHEST

(89 = 39 + 50)

HARDEST

(89 = 39 + 50)

ACHIEST

(89 = 39 + 50)

AITCHES

(89 = 39 + 50)

CRASHED

(89 = 39 + 50)

HARDEST

(89 = 39 + 50)

DEARTHS

(89 = 39 + 50)

CITHERS

(89 = 39 + 50)

REDACTS

(89 = 39 + 50)

SHIRTED

(89 = 39 + 50)

CASHIER

(89 = 39 + 50)

CASHIER

(89 = 39 + 50)

DRASTIC

(89 = 39 + 50)

DACITES

(89 = 39 + 50)

RICHEST

(89 = 39 + 50)

CHASTER

(89 = 39 + 50)

CHASTER

(89 = 39 + 50)

THREADS

(89 = 39 + 50)

DITCHER

(89 = 39 + 50)

CHASTER

(89 = 39 + 50)

SCATHED

(89 = 39 + 50)

CREDITS

(89 = 39 + 50)

AITCHES

(89 = 39 + 50)

CITHERS

(89 = 39 + 50)

RICHEST

(89 = 39 + 50)

TRASHED

(89 = 39 + 50)

CHAIRED

(89 = 39 + 50)

SHADIER

(89 = 39 + 50)

AITCHES

(89 = 39 + 50)

RADICES

(89 = 39 + 50)

CHASTER

(89 = 39 + 50)

SHADIER

(89 = 39 + 50)

DITCHES

(89 = 39 + 50)

DIRECTS

(89 = 39 + 50)

ACHIEST

(89 = 39 + 50)

CITHERS

(89 = 39 + 50)

ACHIEST

(89 = 39 + 50)

THREADS

(88 = 38 + 50)

TRASHED

(88 = 38 + 50)

SCATHED

(88 = 38 + 50)

SHADIER

(88 = 38 + 50)

SHIRTED

(88 = 38 + 50)

DEARTHS

(88 = 38 + 50)

CRASHED

(88 = 38 + 50)

SCATHED

(88 = 38 + 50)

DEARTHS

(86 = 36 + 50)

DEARTHS

(86 = 36 + 50)

THREADS

(86 = 36 + 50)

HATREDS

(86 = 36 + 50)

SIDECAR

(86 = 36 + 50)

TRASHED

(86 = 36 + 50)

SHADIER

(86 = 36 + 50)

CHASTER

(86 = 36 + 50)

HATREDS

(86 = 36 + 50)

AITCHES

(86 = 36 + 50)

HARDEST

(86 = 36 + 50)

HATREDS

(86 = 36 + 50)

DITCHES

(86 = 36 + 50)

HATREDS

(86 = 36 + 50)

RICHEST

(86 = 36 + 50)

HATREDS

(86 = 36 + 50)

TRASHED

(86 = 36 + 50)

HARDEST

(86 = 36 + 50)

TRASHED

(86 = 36 + 50)

TRASHED

(86 = 36 + 50)

CITHERS

(86 = 36 + 50)

DACITES

(86 = 36 + 50)

Your Best
Scrabble
Plays Legendary
Scrabble
Plays

↑

tracheids in Words With Friends™

The word tracheids is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.

Words With Friends™ Letter Score: 15

Highest Scoring Words With Friends™ Play In The Letters tracheids:

TRACHEIDS

(225)

Seven Letter Word Alert: (34 words)

All Words With Friends™ Plays For The Word tracheids

TRACHEIDS

(225)

TRACHEIDS

(138)

TRACHEIDS

(102)

TRACHEIDS

(75)

TRACHEIDS

(69)

TRACHEIDS

(69)

TRACHEIDS

(68)

TRACHEIDS

(64)

TRACHEIDS

(64)

TRACHEIDS

(64)

TRACHEIDS

(63)

TRACHEIDS

(60)

TRACHEIDS

(60)

TRACHEIDS

(57)

TRACHEIDS

(57)

TRACHEIDS

(46)

TRACHEIDS

(46)

TRACHEIDS

(46)

TRACHEIDS

(38)

TRACHEIDS

(38)

TRACHEIDS

(34)

TRACHEIDS

(34)

TRACHEIDS

(34)

TRACHEIDS

(34)

TRACHEIDS

(32)

TRACHEIDS

(32)

TRACHEIDS

(30)

TRACHEIDS

(30)

TRACHEIDS

(30)

TRACHEIDS

(30)

TRACHEIDS

(30)

TRACHEIDS

(30)

TRACHEIDS

(27)

TRACHEIDS

(22)

TRACHEIDS

(20)

TRACHEIDS

(20)

TRACHEIDS

(20)

TRACHEIDS

(20)

TRACHEIDS

(20)

TRACHEIDS

(20)

TRACHEIDS

(20)

TRACHEIDS

(19)

TRACHEIDS

(19)

TRACHEIDS

(19)

TRACHEIDS

(19)

TRACHEIDS

(19)

TRACHEIDS

(18)

TRACHEIDS

(18)

TRACHEIDS

(18)

TRACHEIDS

(17)

TRACHEIDS

(17)

TRACHEIDS

(17)

TRACHEIDS

(16)

The 200 Highest Scoring Words With Friends™ Plays Using The Letters In tracheids

TRACHEIDS

(225)

TRACHEIDS

(138)

DITCHES

(104 = 69 + 35)

DITCHES

(104 = 69 + 35)

DITCHER

(104 = 69 + 35)

CRASHED

(104 = 69 + 35)

DITCHER

(104 = 69 + 35)

SCATHED

(104 = 69 + 35)

DACITES

(104 = 69 + 35)

CRASHED

(104 = 69 + 35)

SCATHED

(104 = 69 + 35)

CHAIRED

(104 = 69 + 35)

CHARTED

(104 = 69 + 35)

TRACHEIDS

(102)

AITCHES

(101 = 66 + 35)

RICHEST

(101 = 66 + 35)

ACHIEST

(101 = 66 + 35)

AITCHES

(101 = 66 + 35)

CASHIER

(101 = 66 + 35)

CHASTER

(101 = 66 + 35)

CITHERS

(101 = 66 + 35)

CREDITS

(98 = 63 + 35)

DIRECTS

(98 = 63 + 35)

CHARTED

(98 = 63 + 35)

DITCHES

(98 = 63 + 35)

SCATHED

(98 = 63 + 35)

DITCHES

(98 = 63 + 35)

SIDECAR

(98 = 63 + 35)

DITCHER

(98 = 63 + 35)

DITCHES

(98 = 63 + 35)

CHARTED

(98 = 63 + 35)

DITCHER

(98 = 63 + 35)

RADICES

(98 = 63 + 35)

CRASHED

(98 = 63 + 35)

CHAIRED

(98 = 63 + 35)

DRASTIC

(98 = 63 + 35)

REDACTS

(98 = 63 + 35)

DITCHER

(98 = 63 + 35)

CHAIRED

(98 = 63 + 35)

CASHIER

(95 = 60 + 35)

CITHERS

(95 = 60 + 35)

TRASHED

(95 = 60 + 35)

ACHIEST

(95 = 60 + 35)

CHASTER

(95 = 60 + 35)

AITCHES

(95 = 60 + 35)

CASHIER

(95 = 60 + 35)

ACHIEST

(95 = 60 + 35)

CASHIER

(95 = 60 + 35)

AITCHES

(95 = 60 + 35)

CITHERS

(95 = 60 + 35)

RICHEST

(95 = 60 + 35)

CITHERS

(95 = 60 + 35)

AITCHES

(95 = 60 + 35)

RACIEST

(95 = 60 + 35)

RICHEST

(95 = 60 + 35)

CHASTER

(95 = 60 + 35)

CRISTAE

(95 = 60 + 35)

SHADIER

(95 = 60 + 35)

DITCHER

(92 = 57 + 35)

CREDITS

(92 = 57 + 35)

CHAIRED

(92 = 57 + 35)

CHARTED

(92 = 57 + 35)

DRASTIC

(92 = 57 + 35)

DITCHES

(92 = 57 + 35)

CHAIRED

(92 = 57 + 35)

CHARTED

(92 = 57 + 35)

CRISTAE

(89 = 54 + 35)

RICHEST

(89 = 54 + 35)

HARDEST

(89 = 54 + 35)

HATREDS

(89 = 54 + 35)

DITHERS

(89 = 54 + 35)

SHIRTED

(89 = 54 + 35)

DEARTHS

(89 = 54 + 35)

CHASTER

(89 = 54 + 35)

DITHERS

(89 = 54 + 35)

RICHEST

(89 = 54 + 35)

CITHERS

(89 = 54 + 35)

CASHIER

(89 = 54 + 35)

CASHIER

(89 = 54 + 35)

CITHERS

(89 = 54 + 35)

THREADS

(89 = 54 + 35)

CHAIRED

(87 = 52 + 35)

SCATHED

(87 = 52 + 35)

CRASHED

(87 = 52 + 35)

DITCHER

(87 = 52 + 35)

CHAIRED

(87 = 52 + 35)

CHAIRED

(87 = 52 + 35)

CRASHED

(87 = 52 + 35)

DITCHER

(87 = 52 + 35)

CRASHED

(87 = 52 + 35)

SCATHED

(87 = 52 + 35)

CHARTED

(87 = 52 + 35)

DITCHER

(87 = 52 + 35)

DITCHES

(87 = 52 + 35)

CHARTED

(87 = 52 + 35)

DITCHES

(87 = 52 + 35)

CHARTED

(87 = 52 + 35)

DITCHES

(87 = 52 + 35)

SCATHED

(87 = 52 + 35)

CREDITS

(86 = 51 + 35)

CHAIRED

(86 = 51 + 35)

DITCHES

(86 = 51 + 35)

CHARTED

(86 = 51 + 35)

SIDECAR

(86 = 51 + 35)

SCATHED

(86 = 51 + 35)

REDACTS

(86 = 51 + 35)

CRASHED

(86 = 51 + 35)

SCATHED

(86 = 51 + 35)

CRASHED

(86 = 51 + 35)

CREDITS

(86 = 51 + 35)

SCATHED

(86 = 51 + 35)

HASTIER

(86 = 51 + 35)

DRASTIC

(86 = 51 + 35)

RADICES

(86 = 51 + 35)

DITCHER

(86 = 51 + 35)

CHARTED

(86 = 51 + 35)

CRASHED

(86 = 51 + 35)

CHAIRED

(86 = 51 + 35)

DIRECTS

(86 = 51 + 35)

SHADIER

(83 = 48 + 35)

RICHEST

(83 = 48 + 35)

AITCHES

(83 = 48 + 35)

AITCHES

(83 = 48 + 35)

DITHERS

(83 = 48 + 35)

DITHERS

(83 = 48 + 35)

DEARTHS

(83 = 48 + 35)

ACHIEST

(83 = 48 + 35)

CHASTER

(83 = 48 + 35)

ACHIEST

(83 = 48 + 35)

CHASTER

(83 = 48 + 35)

CITHERS

(83 = 48 + 35)

AITCHES

(83 = 48 + 35)

CASHIER

(83 = 48 + 35)

HARDEST

(83 = 48 + 35)

AITCHES

(83 = 48 + 35)

CHASTER

(83 = 48 + 35)

HARDEST

(83 = 48 + 35)

CITHERS

(83 = 48 + 35)

HATREDS

(83 = 48 + 35)

CHASTER

(83 = 48 + 35)

DITHERS

(83 = 48 + 35)

RICHEST

(83 = 48 + 35)

CITHERS

(83 = 48 + 35)

CASHIER

(83 = 48 + 35)

RICHEST

(83 = 48 + 35)

HATREDS

(83 = 48 + 35)

SHIRTED

(83 = 48 + 35)

CITHERS

(83 = 48 + 35)

SHIRTED

(83 = 48 + 35)

SHADIER

(83 = 48 + 35)

HARDEST

(83 = 48 + 35)

RICHEST

(83 = 48 + 35)

CASHIER

(83 = 48 + 35)

CASHIER

(83 = 48 + 35)

ACHIEST

(83 = 48 + 35)

ACHIEST

(83 = 48 + 35)

THREADS

(83 = 48 + 35)

DEARTHS

(83 = 48 + 35)

THREADS

(83 = 48 + 35)

CHASTER

(83 = 48 + 35)

ACHIEST

(83 = 48 + 35)

DACITES

(80 = 45 + 35)

CRASHED

(80 = 45 + 35)

RADICES

(80 = 45 + 35)

SCATHED

(80 = 45 + 35)

REDACTS

(80 = 45 + 35)

SCATHED

(80 = 45 + 35)

CHAIRED

(80 = 45 + 35)

SCATHED

(80 = 45 + 35)

CREDITS

(80 = 45 + 35)

REDACTS

(80 = 45 + 35)

DACITES

(80 = 45 + 35)

CHAIRED

(80 = 45 + 35)

DACITES

(80 = 45 + 35)

DIRECTS

(80 = 45 + 35)

DACITES

(80 = 45 + 35)

DITCHER

(80 = 45 + 35)

CRASHED

(80 = 45 + 35)

CHARTED

(80 = 45 + 35)

DRASTIC

(80 = 45 + 35)

SCATHED

(80 = 45 + 35)

SIDECAR

(80 = 45 + 35)

HASTIER

(80 = 45 + 35)

DITCHES

(80 = 45 + 35)

RADICES

(80 = 45 + 35)

DRASTIC

(80 = 45 + 35)

CRASHED

(80 = 45 + 35)

SIDECAR

(80 = 45 + 35)

DIRECTS

(80 = 45 + 35)

CHARTED

(80 = 45 + 35)

DITCHES

(80 = 45 + 35)

CREDITS

(80 = 45 + 35)

CREDITS

(80 = 45 + 35)

CHARTED

(80 = 45 + 35)

DITCHER

(80 = 45 + 35)

DRASTIC

(80 = 45 + 35)

CHAIRED

(80 = 45 + 35)

DITCHES

(80 = 45 + 35)

DITCHER

(80 = 45 + 35)

DIRECTS

(80 = 45 + 35)

Legendary
Words With Friends
Plays Your Best
Words With Friends
Plays

↑

Words within the letters of tracheids

2 letter words in tracheids (15 words)

ad ah ai ar as at eh ha he hi id is it re ta

3 letter words in tracheids (55 words)

ace act ads aid air ais arc are ars art ash ate cad car cat chi cis die ear eat era eta had has hat her hes het hic hid his hit ice ide ids ire its rat red rid sac sad sat sea set she sic sir sit tad tar tea the tic tie

4 letter words in tracheids (117 words)

5 letter words in tracheids (156 words)

7 letter words in tracheids (34 words)

8 letter words in tracheids (6 words)

chariest ditchers hardiest rachides starched tracheid

9 letter words in tracheids (1 word)

tracheids

tracheids + 1 blank (3 words)

catharised dispatcher rhotacised

tracheids + 2 blanks (7 words)

achondrites birdwatches chloridates dichromates dispatchers predispatch thickspread

↑

Words containing the sequence tracheids

Words that start with tracheids (1 word)

tracheids

Words with tracheids in them (1 word)

tracheids

Words that end with tracheids (1 word)

tracheids

↑

Word Growth involving tracheids

Shorter words in tracheids

id ids

he ache tracheid

id tracheid

Longer words containing tracheids

(No longer words found)

Definition of tracheids

"tracheids" in the noun sense

1. tracheid

tracheids in Scrabble®

Scrabble® Letter Score: 15

Highest Scoring Scrabble® Play In The Letters tracheids:

Seven Letter Word Alert: (34 words)

All Scrabble® Plays For The Word tracheids

The 200 Highest Scoring Scrabble® Plays For Words Using The Letters In tracheids

tracheids in Words With Friends™

Words With Friends™ Letter Score: 15

Highest Scoring Words With Friends™ Play In The Letters tracheids:

Seven Letter Word Alert: (34 words)

All Words With Friends™ Plays For The Word tracheids

The 200 Highest Scoring Words With Friends™ Plays Using The Letters In tracheids

Words within the letters of tracheids

2 letter words in tracheids (15 words)

3 letter words in tracheids (55 words)

4 letter words in tracheids (117 words)

5 letter words in tracheids (156 words)

6 letter words in tracheids (92 words)

7 letter words in tracheids (34 words)

8 letter words in tracheids (6 words)

9 letter words in tracheids (1 word)

tracheids + 1 blank (3 words)

tracheids + 2 blanks (7 words)

Words containing the sequence tracheids

Words that start with tracheids (1 word)

Words with tracheids in them (1 word)

Words that end with tracheids (1 word)

Word Growth involving tracheids

Shorter words in tracheids

Longer words containing tracheids