KEY TO SUB-CLASSES, ORDERS AND GENERA. 158 
XT.IX—MYRTACEA—cont, 
a rule immediately under the epidermis. In leaves these oil cavities may often be seen 
as translucent points. Further, there are strands of phloem in the circumference of the 
pith, usually without thick walled bast fibres. Apart from the medullary rays, which 
are always narrow, parenchyma does not form an important element in the wood. 
LEcYTHIDACE® have no oil cavities and there is no phloem in the pith, transverse bars 
of parenchyma are not uncommon between the rays. The chief character, however, of 
the last named order is that the leaf traces (vascular bundles), which enter the petiole, 
separate from the central cylinder some distance below the insertion of the leaf. 
Hence the tyansverse section of «a branchlet shows, a8 is the case in Dipterocarps, a 
number of vascular bundles in the bark. In the petiole und midrib these vascular 
bundles do not coalesce, but remain distinct, | 
(1) (fyrraces® proper)-——Leaves opposite, rarely alternate, gland-dotted :— 
(i) Ovary 2—5-celled; fruit capsular, opening by as many valves; leaves 
mostly alternate :— 
(1) Stamens numerous, in a continuous series in a single row, shorter 
than the petals ; leaves small or narrow, alternate ; flowers solitary, or crowded 
buat not in heads :— : ees cdxiv--Leptospormun. 
(2) Stamens numerous, free (or ‘obscurely united at base), shorter than 
the petals, which are attached by a broad base and consolidated -into an oper- 
culuim, and fall off in one piece as the flower opens; calyx truncate, entire or 
with 4 minute teeth ; flowers in heads, cymes, or umbels, rarely sessile on the 
stem ; Jeaves alternate (opposite in 1 spevies and occasionally on young shoots of 
other species), usually large :— AE ay ... ¢dix-—Eucalyptus, 
(8) Stamens exceeding the petals : -- 
(A) Leaves small or narrow (rarely large and many nerve), alternate ; 
flowers closely sessile :— 
(a) Stamens free ; calyx-lobes deciduous ; ovary 8—4-celled; seeds 
ascending ; flowers in spikes, either terminal or crowned by the 
leaves of the year’s shoot:— . .» edxii——Callistemon, 
(b) Stamens in 5 bundles opposite the petals ; flowers in heads or 
spikes, the axis of the spike growing during or after flowering, 
the fruiting spike forming the base of a new branch :— 
cdxv—-Melaleuca. 
(B) Leaves large or myrtle-like, penninerved ; flowers in pedunculate 
heads or cymes :— 
(a) Leaves alternate (in T. neriifolia, opposite) ; stamens united in 
5 bundles ; flowers in axillary cymes ;-- .. ¢cdxvi—Tristania, 
(b) Leaves opposite; stamens free; flowers in globular involucrate 
heads at the base of new shoots :-— 50 ... cdxili—Syncarpia. 
(ii) Ovary 2 or more-celled (Rhodamnia 1-celled with 2 parietal placentas) ; 
fruit a berry or drupe ; leaves mostly opposite (sometimes Eugenia 3-whorled, 
and 1 species alternate) :— 
(1) Leaves 3-costate from base ; peduncles 1-—3-flowered :—- 
(A) Ovary 1-celled, ovules numerous on 2 parietal placentas ; flowers 
smal] :-— .. ¢dxviti—Rhodamnia, 
(B) Ovary 1—3- celled, with double rows of ovules i in each cell separated 
again by spurious septa; flowers_medium, pink; leaves hoary- 
tomentose backed :— cdxix.—Rhodomyrtus. 
(2) Leaves pennineryed :— 
(A) Limb of calyx closed in bud, lobes subimbricate, rather deeply 
valvately separated when in flowers ; seeds numerous :— 
cedxvii—Psidium. 
(B) Limb of calyx 4—5-lobed or-partite in bud, not further divided in 
flower ; seeds not numerous :— 
(a) Ovules pendulous from top of the locules; flowers small in 
trichotomous cymes from the upper axils :~— .. Cdxi-—Pimenta. 
(b) Ovules from whole inner angle, or from a somewhat prominent 
septal placenta :-- 
(c) Ovary 4—5-celled ; seeds several though not numerous :-- 
(*) Peduncles 1-flowered : ee = aa .. eds—Myrtus. 
