while the present invention is open to various modifications and alternative constructions , the preferred embodiments shown in the drawings will be described herein in detail . it is to be understood , however , there is no intention to limit the invention to the particular forms disclosed . on the contrary , it is intended that the invention cover all modifications , equivalences and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims . referring to fig1 and 3 , a plant injection dispensing capsule 20 according to a first embodiment of the invention includes a cap 22 having a circumferential , generally circular edge 23 hermetically sealed to a circumferential , generally circular rim 25 of a receptacle 24 . as best shown in fig3 receptacle 24 has an interior volume determined by a circumferential , generally cylindrical wall 26 , terminating upwardly in rim 25 , which is generally orthogonal to a generally planar floor 28 having an upper surface 28 s . depending upwardly from floor 28 and proximate to its center of symmetry is an upwardly tapering spindle 30 , in the shape of a conical frustum , having an outer surface 30 s , a top 31 and a bore 32 . receptacle 24 further includes a housing 34 attached to wall 26 which provides a generally planar force application surface 35 , a hollow base 36 for the capsule , and structural support for the wall . as shown in fig2 ribs 38 a , 38 b , 38 c are attached between an interior surface 40 of housing 34 , and wall 26 and floor 28 . wall 26 includes an aperture 42 proximate to floor 28 and external to housing 34 into which is inserted an inner end 44 a of a feeder tube 44 ( not part of the invention ) having an outer end 44 b terminating in an outlet 46 . alternatively , the aperture may be internal to the housing . as is described below , and in an illustrative technique , feeder tube outer end 44 b is inserted into a predrilled hole in a tree trunk or plant stem and the aperture 42 of a pre - pressurized capsule is slidably positioned over the feeder tube inner end 44 a to secure the capsule to the feeder tube . preferably , receptacle 24 is molded as a single unit from polypropylene or a similar thermoplastic . most preferably , the receptacle is molded from a clarified polypropylene copolymer which includes propene , ethene and modifiers / additives , such as product p5m6k - 048 available from huntsman polymers corporation of houston , tex . referring to fig4 a and 4b , cap 22 includes a rigid central portion 50 circumscribed by a plurality of concentric annuluses 52 a , 52 b , 52 c bridged consecutively pairwise , respectively , by a plurality of stepped ridges 54 a , 54 b , 54 c generally orthogonal to the annuluses so that the cap initially is convexly arcuate . the ridges act as “ living hinges ” enabling cap 22 to flex inwardly when a downward force , as by a thumb , is applied to central portion 50 , depressing the portion . depending downwardly from portion 50 is a socket 60 terminating in an end 60 e and having a hexagonal - shaped bore 62 determined by a plurality of generally planar surfaces 64 a , 64 b , 64 c , 64 d , 64 e , 64 f . preferably , cap 22 is molded as a single unit from polypropylene or a similar thermoplastic . most preferably , the cap is molded from a clarified polypropylene copolymer such as huntsman product p5m6k - 048 . [ 0036 ] fig5 depicts capsule 20 in its initial ( unpressurized ) state . receptacle 24 contains a preselected amount of a therapeutic liquid composition 66 having a surface 66 s . ( for clarity of the other first embodiment figures , liquid composition 66 is shown only in fig5 .) preferably , the amount of liquid is in a range from about 1 to about 6 milliliters ( ml ). for a greater amount up to about 25 ml , a compressible cap with a higher profile than cap 22 should be used to provide greater displacement for developing a suitable dispensing pressure . spindle 30 is closely received within socket bore 62 . because cap portion 50 has not yet been depressed , socket end 60 e is disposed only about halfway down the spindle . floor 28 includes a channel 68 in surface 28 s proximate to aperture 42 which ensures that even a small amount of liquid within the receptacle will be accessible to the aperture and thence the feeder tube . aperture 42 is sealed by a dislodgeable “ knockout ” membrane 70 . as indicated by grooves 70 a , 70 b in fig5 and 6 b , the membrane includes a peripheral annular thinned - out portion which contacts the receptacle wall . fig6 depicts capsule 20 after portion 50 has been depressed , pre - pressurizing the capsule , tube end 44 b has been inserted into a pre - drilled hole 72 h in a tree trunk or plant stem 74 , aperture 42 has been slidably positioned over tube end 44 a , and a force 76 has been applied to surface 35 such that tube end 44 a dislodges membrane 70 . spindle 30 is forced deeper into bore 62 so that end 60 e becomes proximate to floor 28 . socket 60 is maintained in this position by an interference fit between surface 30 s and surfaces 64 a - 64 f . tube end 44 a is adapted to dislodge membrane 70 circumferentially except at an upper end 70 u so that the membrane pivots inwardly ( see fig6 b ). alternatively , a frangible membrane may be used with the tube end adapted for rupturing rather than dislodging the membrane . fig6 a shows how the cap attaches to the receptacle . edge 23 includes generally parallel upper and lower lips 23 u , 23 l , respectively . rim 25 includes an upper surface 25 s and a lip 25 l . lip 23 u mates with surface 25 s , and lip 23 l mates with lip 25 l . preferably , edge 23 and rim 25 are attached by ultrasonic welding . suitable welders are manufactured by branson ultrasonics corporation of danbury , conn . preferably , capsule 20 is about 2¼ inches in length , 2⅛ inches in width , and 1⅜ inches in height . referring to fig1 and 8 , a plant injection capsule 100 according to a second embodiment of the invention includes a cap 102 having a circumferential , generally circular edge 103 hermetically sealed to a circumferential , generally circular rim 105 of a receptacle 104 . the cap and receptacle are attached as in the first embodiment ( see fig6 a ), preferably by ultrasonic welding . as shown in fig7 receptacle 104 has an interior volume determined by a circumferential , generally cylindrical wall 106 , terminating upwardly in rim 105 , which is generally orthogonal to a generally planar floor 108 having an upper surface 108 s . receptacle 104 further includes a housing 140 attached to wall 106 which provides a generally planar force application surface 142 . attached to and depending upwardly from floor 108 and generally symmetric about its center of symmetry are first , second and third posts 110 a , 110 b , 110 c each having a hook - shaped upper portion 112 with a generally planar lower surface 112 s , and a lower portion 114 generally orthogonal to surface 112 s . as in the first embodiment , wall 106 includes an aperture 116 proximate to floor 108 . referring to fig8 and 9 , the top of cap 102 is identical to that of cap 22 ; i . e ., the cap includes a rigid central portion 118 circumscribed by a plurality of concentric annuluses 120 a , 120 b , 120 c bridged consecutively pairwise , respectively , by a plurality of stepped ridges 122 a , 122 b , 122 c which enable the cap to flex inwardly . depending downwardly from portion 118 is a generally cylindrical collar 124 having a bore 126 and a distally tapering end portion 128 terminating in an end 128 e . portion 128 includes a circumferential groove 130 proximate to end 128 e which determines an annular lip 132 having a generally planar upper surface 132 s . fig9 and 10 depict capsule 100 in its initial ( unpressurized ) state , with end 128 e disposed slightly above the posts . ( as in the first embodiment , receptacle 104 contains a preselected amount of liquid composition ; for clarity this is not shown in any of the second embodiment figures . the preferred amount is in the same range as for the first embodiment .) as in the first embodiment , floor 108 includes a channel 134 in surface 108 s proximate to aperture 116 , and aperture 116 is sealed by a dislodgeable membrane 136 . as indicated by grooves 136 a , 136 b ( see fig9 and 11 ), the membrane includes a peripheral annular thinned - out portion which contacts the receptacle wall . fig1 and 12 depict capsule 100 after portion 118 is depressed , pressurizing the capsule , aperture 116 is slidably positioned over feeder tube end 44 a after tube end 44 b is inserted into a tree trunk or plant stem ( see fig6 ), and a force 144 is applied to surface 142 , dislodging membrane 136 . collar 124 is forced downward so that lower surfaces 112 s of posts 111 a , 110 b , 110 c engage surface 132 s . the resilience of the cap “ living hinge ” maintains the surfaces in locked combination . as in the first embodiment , preferably cap 102 and receptacle 104 are molded as single units from polypropylene or a similar thermoplastic , and most preferably from a clarified polypropylene copolymer such as huntsman product p5m6k - 048 . preferably , capsule 100 has the same dimensions as capsule 20 .
a disposable dispensing capsule for a plant injectable liquid composition includes a flexible cap hermetically sealed to a receptacle . the capsule is pressurized when the cap is forcibly flexed inwardly . in one embodiment flexure and thereby pressurization are maintained by an interference fit between a spindle in the receptacle and a socket depending downwardly from the cap central portion . in another embodiment flexure is maintained by engagement of hook - shaped posts in the receptacle with a lip in a collar depending downwardly from the cap central portion .